I just ordered a Pioneer 105 from LiveWarehouse for $230. I couldn't wait any longer, but from time to time, Staples.com runs a great sale (rebate) on the Cendyne DVD burner, which is a Pioneer 105 under the hood. I've seen it for $150 a couple months ago.
Also, search around these threads and the web for info on doing this. First of all, it appears that for the Apple apps to recognize this drive, you have to replace your main optical drive with the Pioneer - it has to be internal and has to be the primary drive.
If you can't find info, let me know and I'll dig up the info I've found.
But yes, if you want to use the Apple apps, right now you pretty much need to have a Pioneer 105/A05 drive.