depends on a lot of things, I think 10,000 is easily a safe reg for a .com, as long as you hit the search term bang on. if it's a two or three word term, you have to be careful what order the words are in, and check if any should be plural.
if you are regging strictly for PPC or developing with adsense ads, then you have to make sure the term can pull some decent paying keywords.
there are other factors, like the term may be in your industry, or have close personal meaning, or there is reason to believe the overture will increase over time.
If it's a short one word in .com then it's probably worth regging at 800, unless it might be a typo of another word? At the 800 level, it starts depending on the other factors - like keyword value, future potential, etc. If it's taking a long time to decide then there must be some kind of value to you there, so just reg it. good luck