It depends on exactly what you mean by 'control'.
If you, the attacker, get to choose two files that should have the same hash, that's what cryptographers call a collision (attack) and for MD5 it's now very easy. If you can choose both files freely it takes seconds; if you have to satisfy fairly weak but common constraints like 'it looks like a PDF' or 'it looks like a tar' maybe hours to weeks.
On the other hand if you have one file pre-specified (usually a 'good' one) and you must find another ('bad') file with the same hash, that is not a collision to cryptographers, it is a second preimage. The best known preimage attack on MD5 is only slightly better than brute force at 2123.4.
Your $5k can probably buy half a dozen good GPUs, which gives you somewhere in the vicinity of 237 trials per second (about 100 billion). That is roughly 262 per year, so it will take on average about 260 years (about 1,000,000,000,000,000,000 aka a quintillion). In more convenient terms, that is about a hundred million times the age of the universe. Your computer probably won't last that long.