Blue Pendant of Hope, Blue Hammer of Capability, Yellow Plough of Plenty, Yellow Warhammer of Justice +1, gaining 124+ mana for 145gp.

Do not gamble with green items or the red pendant of truth; the value of a good, lucrative client with a somewhat useful sensing device and your own credibility is worth much more than some gold pieces today.

Regularities found:

• blue items register +/- 1 on the thaugister, except jewelry gets a +22
• weapon mana is at least 10x the bonus and no more than 10(x+1) the bonus
• (axes and hammers are tools, not weapons)
• yellow items yield 18-21 mana
• green items are capped at 40 mana and their thauyard readings seem very uncorrelated
• actually all jewelry gets a +22 to its thaudout
• jewelry-adjusted blue-adjusted thaulues are at most 60
• red mana is always some product of 2s, 3s, and 5s
• green items always yield an even amount of mana
• non-blue items have thauras whose only prime factors are 2, 3, 5, or 7
• green items yield mana whose prime factorization's non-2 exponents sum to at most 2, and only if exactly 1 from bases greater than 5
• some identical red and green items have wildly different mana/thauata

200gp, 120m? We can get that with Blue Pendant of Hope, Blue Hammer of Capability, Yellow Plough of Plenty, Yellow Warhammer of Justice +1, gaining 124+ mana for 145gp. Definitely take the job, and try to figure out on the road what's up with the Red Pendant of Truth and all the Green items. A good Green item saves ~30gp, but if we can know the Red Pendant of Truth is great we could save even more.

Crucially, no probabilistic choices should be made, for three reasons:

• You have no guarantee about the distribution of item stats presented. They are very likely not uniform random. In fact meta-you suspects that there was once a list of 1000 items and 164 got filtered out.
• You have a good client who is handing you 55gp for a day's work. This is an excellent situation. It is far better to keep this client than to try to eke out additional gold for this particular job.
• Further, you have valuable information. You know what the client's thaudget does with jewelry and items with a blue glow, and you know how weapon mana and bonuses are related, and you know the yield of items with a yellow glow, and you know the maximum yield of items with a green glow. You can use this information in future deals with the client, or, if you can arrange a more profitable deal for the information itself, perhaps land a major score. But this second possibility is far, far less likely if you accidentally damage your credibility by supplying less than 120 mana.

X-Y chart of mana vs thaumometer looked interesting, splitting it into separate charts for each colour returned useful results for blue:

• blue gives 2 diagonal lines, one for tools/weapons, one for jewelry - for tools/weapons it's pretty accurate, +-1, but optimistic by 21 or 23 for jewelry

and... that's basically it, the thaumometer seems relatively useless for the other colours.

But: 

green gives an even number of mana that looks uniformish in the range of 2-40

yellow always gives mana in the range of 18-21

red gives mana that can be really high, up to 96, but is not uniform, median 18

easy strategy: 

pendant of hope (blue, 77 thaumometer reading -> 54 or 56 mana expected), 34 gp

hammer of capability (blue, 35 thaumometer reading -> 34 or 36 mana expected), 35 gp

Plough of Plenty (yellow, 18-21 mana expected), 35 gp

Warhammer of Justice +1 (yellow, 18-21 mana expected), 41 gp

For a total of at least 124 mana at the cost of 145 gp, leaving 55 gp left over

Now, if I was doing this at the time, I would likely investigate further to check if, say, high red or green values can be predicted.

But, I admit I have some meta knowledge here - it was stated in discussion of difficulty of a recent problem, if I recall correctly, that this was one of the easier ones. So, I'm guessing there isn't a hidden decipherable pattern to predict mana values for the reds and greens.

// Plotting a graph of reading v colour reveals the following.
//- Blue somewhat erratic but definite trend of increasing mana with increasing reading
//  The erratic part is in the 22 - 63 range, before and after steady increase/decrease.
//- Green  seems to fluctuate in the 2- 40 range regardless or reading
//- red erratic all over the place, no consistent pattern
//- yellow seems to fluctuate in the 18 - 21 range regardless of reading
//
// Green has an average mana of 21, red 25 , though green seems to have fewer with really low values.
//
// There is no obvious correlation based on the items name.
// Eliminating obviously uneconomic items suggest the following are realistic:
//Pendant of Hope         54 mana      34 gold    BLUE
//Ring of Joy             10-30 mana   32 gold    BLUE
//Hammer of Capability    15-35 mana   35 gold    BLUE
//Warhammer of Justice +1 18-21 mana   41 gold    YELLOW
//Plough of Plenty        18-21 mana   35 gold    YELLOW
//Saw of Capability +1    avg 21 mana  35 gold    GREEN
//Amulet of Wounding +2   avg 21 mana  35 gold    GREEN
//Pendant of Truth        avg 25 mana  38 gold    RED
//
// Pendant of Hope is obviously the best. Could reach target with near 100 percent certainty with top 5 items
// leaving me with 23 gold.
//
// Pendant of Hope + Saw of Capabilty + amulet of Wounding + Pendant of Truth would leave me with 58 gold
// if it worked, but would probably fail just under 50 percent of the time. This could be reduce significantly
// by paying 32 gold, but that would only leave me with 3 gold more, and still looks less certain.
//
// As avoiding being in debt by 200 gold is probably much more important to me than gaining 25 gold I will go
// for what looks to be the safe option of:
// Pendant of Hope
// Ring of Joy
// Hammer of Capability
// Warhammer of Justice + 1
// Plough of Plenty
// And hopefully 23 gold.