Its a goodman part, a dozen places will have it and sell it to anybody, but I think that is NOT a smart idea.
Since I am cheap too let me speak plainly, Have you considered that your friends friend gave you a price that includes a bit of profit for himself? Pay for doing this job?
Pop H29B35UABCA Bristol into either of these search engines;
Look at the price, but don't talk about it here, and think for a few minutes about just what the situation is. Is your friends friend too stupid not to know how common a 10 seer bristol compressor is or how to cross check parts? Do you REALLY think its happy news to help him shop? Replacing the compressor is more work than replacing the whole outside unit I bet.
Frankly I think you are wasting both time and money by not replacing the whole AC NOW, if you are stuck with the terms of sale, buy a window unit and stay in one room.