One option would be to be more assertive with the real estate agent. Tell him/her that you don't see in the lease how the seller has the right to kick you out, since it's a year-to-year lease and nowhere does it say they can just give you 30/60 days notice. And it's going to cost you time and money to move voluntarily. But since I'm such a nice guy, here's what I can do:
1) I will find a new place
2) Once I have a lease ready to sign at the new place, I will vacate my current apartment within 5 days of the move-in (so you have a little overlap)
3) I want 100% of my security deposit back, no questions asked, because I have moving expenses and am doing the owner a favor by making this easy. I need that money now, to move into my new place.
4) I'll sign something terminating the lease once I have my deposit back.
Keep in mind the real estate agent wants the commission on the sale and as few headaches as possible, and your deposit is probably peanuts in the grand scheme to them.
You can of course always demand more, and if you do want to fight any of it, tenants are well protected under the law.