GVdialer is being relaunched at a lower price point, but I can wait.
iPhonefreak has a very encouraging review of GV Mobile that mentions a few others ...
Aside from GV Mobile, there are also three other Google Voice apps for the iPhone that I am aware of. They include VoiceCentral, GVdialer and a third that I cannot name just yet..I've read that there's no Google Voice API yet, so all apps need to do the modern equivalent of "screen scraping". Even so they're able to offer some great features like Contacts integration, SMS integration (no charge for sending!) and outgoing calls showing one's GV number rather than the mobile phone number.
Of course Google has a "mobile" web client for GV, but it's miserable. I prefer to simply call my GV number from my phone, tap '2', then tap in the number I'm dialing, tap # and go. Since I'm really only calling one number from GV that's tolerable for now. I assume they'll deliver something better in time but I bet they're currently focusing on the GV API (that's where things get even more fun).
Unless the initial reviews are as bad as those for GVdialer, I'll be reporting on my GV Mobile experiences once that app is available. It will launch with a free "lite" version as well as the pay version -- that's a good sign of a quality product in the rapidly evolving App store scene.
PS. I'm so impressed by the iPhoneFreak review I'm adding them to my bloglist for a test.