[rdlsmith]

I've been using this one:

BUFFALO MiniStation Plus 1 TB USB 3.0 Portable Hard Drive - HD-PNT1.0U3B I bought that from Amazon and now I think they've dropped quite a bit in price. There may be a newer model available.

It's bus powered which is nice. I've been using with a MBP but tested it on my 27" iMac from late 2012. It's not as fast as the seagate thunderbolt I use but it's a worthy drive and so far has worked fine. I bought it in early February 2013 and use it once per week to image the MBPs HD. However, I haven't used it with Mavericks yet.