I've been using an avrispmkii clone (ebay) for quite some time and I'm happy with it, but I'm not sure if it's still available. I bought it to be able to program the newer Xmega chips, which requires "PDI" support.
If all you care for is programming "the usual" attiny / atmega chips via "ISP", you should be OK with any of these (in no particular order):
* usbtiny (adafruit)
I don't know which OS you use, so you may or may not have to install drivers. Some of these programmers may not be able to program devices with more than 64kb of flash memory, best to check the vendor page for specific chip support. This obviously won't be an issue with the ATtiny13, but I thought I should mention it.