About 12 months ago I tried to add the prize money of a race as part of a ratings system for West Aus races. I would give the horse xKg performance bonus in each race depending on the prize money of each previous race it had had. It was only part of a larger rating system so it didn't have a huge effect on the final rating of the horse.
I was dismayed to find that it actually reduced my POT by a small amount.
So I did the opposite. Reduced the horse's rating based on the prize money of the previous races, and lo and behold the POT improved marginally.
What a load of crap I hear you say, how can that be. Well, if I am on foriegn soil (like when holidaying in NZ for eg) and I feel like a few $1 bets to make life interesting I might have a formguide in front of me. I don't know any of the races or the horses and one of the things I base my selections on is the prize money of the previous races, thinking they will be a guide to the strength of the horses. If I do this as one of my first options (in the blackness of ignorance) I guess perhaps others do the same and so maybe prizemoney of previous races is overused by the mug punter. Since that experiment I have put prizemoney of previous races in the same category as barriers, overused by punters and thus a negative influence on POT.

Having said all this, I relate this more for interests sake than anything else, you are using it in a totally different way so maybe it will pull its share of winners.

KV