Conformation shots (her standing square, left, right, front, back) would be helpful. Not every mare is suitable for breeding, same as not every stallion should be a stallion. Is she a stock type, halter, or race type? Does she have anything outstanding in her pedigree?
Consider what you want to do with the foal, and your overall experience with horses. Currently, the market is really in the pits. Their are lots of registered Paint and QH colts and fillies for $300 or less. Occasionally their nice, but most of the time they have glaring conformation faults. Pretty colors, yes, but with with butts over their withers, sway backs, crooked feet, coarse heads, horrible necks etc.
First, look at the foal for yourself. What you want to do with, etc. Then look at it's sale value. Would you be able to sell the foal for $900+? Or for $500-? Are you able to afford vet fees, farrier, boarding (if you board) for two horses? What about time? Have you trained horses, or ridden advanced horses before? Or could you afford a real, quality trainer?
Also, consider the sire. Are you able to go with the working stallion with good lines who produces correct, quality foals? Or the stud who's done nothing but is a pretty color?
I'm all for breeding your own horses. I love horses, and I love foals. But these are the exact same questions I asked myself when I wanted to breed a foal. They may seem harsh, but they certainly are a reality check :)
Wait! I'll fix it....