I agree. PocketMoney. I think that there is a very restricted light version that is a free download that you can try first but the full version really is feature packed and it's under very active development. Just go to
http://catamount.com/forums/ and look how active the forums are and how often the developer (Hardy Macia) posts there.
It also has the advantage that in the next month or so it will be able to sync between versions on the iPhone and iPad (it can already do it in a crude way by emailing transactions between devices but the syncing is being really beefed up in version 3.1 due in the next few weeks but probably September before it hits the App Store) and in about another month there will be desktop clients for the PC (and the Mac I think, I'm a PC guy myself) that can also sync with the iPhone and iPad versions.
It's not cheap compared to some of the other stuff out there but you get what you pay for, and with PocketMoney you get a lot.
Oh, I note that you said "a great budget app". The budgetting bit of the app is going to be the focus of development for version 3.2 which the developer is hoping to release to the approval process in September so in either late Sep or early Oct there should be lots of enhancements to the bugetting capabilities that you see in the current version.
- Julian