Buy 50 servers and start leasing VPS for $19 a month. 1000 clients will leave 20k a month enough to pay a sysadmin and pocket some cash while you monitor everything from hawaii.
also, you are probably better off with dual-socket servers w/ at least 32GiB ram, which will cost you considerably more than a grand each, but that will likely get you more power/ram for your money. For a grand a pop, you are probably looking at 8G ram servers, so if you are trying to put 1000 customers on those puppies, you are going to be coming in at around twice what I charge, and pretty close to what Linode charges. Linode is very good and very established, and they have an excellent toolset. You will need to spend a lot of marketing dollars to say "Hey you've never heard of me, but pay me just as much as you'd pay the established player with the good reputation"
If you still really want to do it, go buy my book[1] - I've included much of what I learned running my own VPS company.
(that said, I'm not saying you are wrong; owning infrastructure and renting it out usually has a reasonable and predictable (and not huge) upside.)