My E90 M3 lease (take over) is up end of January. I plan to buy mine out. It really depends on your car's value vs it's residual buy out and your own finances.
For mine, the original owner had a 15k mi/yr lease and drove slightly under that. When I took over I drove waaay under that and now I have a low to moderate miles vehicle with a low residual. I think my real value will be about $4-5k over the residual. Now I do have to pay tax if I buy though and in Seattle it's 9.8% for cars, so.... ouch. That $4-5k "equity" pretty much disappears. Still, I won't be underwater if I buy out and with each purchase payment I'll be further ahead of the depreciation.
There's a lot of factors and numbers to think about with this, but with a purchase option you could come out ahead in the end, even if it's only 6-9 months you're talking about.
Alternatively, buy a $3000 Civic for 6 months.
