Dollhouse is no Firefly and I cannot recommend it for anything other than "borrowing a friend's copy" type viewing.
Depending on discretionary income, Season 1 is like $10. Season 2 is like $35.
I bought both as a xmas present to myself, and it was a great re-watch over the holidays. (I had never watched either Epitath episode, so that was a bonus)
I could see myself watching the second half of season 1 and season 2 again sometime.