I wish it was in the budget for us. DD has had amazing head and neck control for months, and starts yelling at us if she's NOT sitting up.
It's her favorite position, and any time she's even remotely reclining, she fights tooth and nail to pull herself in to a sitting position. I think a few minutes a day might make her happy, kwim?
Unfortunately we have no money, nor do I know anyone who doesn't use theirs anymore. Oh well. She'll probably be sitting by herself soon enough, or we'll just keep propping her up on the couch, although she yells if we go out of eyesight.