www.kevinkienlein.com wrote:

I have a canon digital rebel and a Tamron 28-200 f3.8-5.6, I am looking at
buying a 2x teleconverter on eBay for under $100.



Are any brands better than others, are they bad news or should I just buy
a canon 75-300 for around $300 and not waste my money... ?

You will loose 2 stops of light and it will not autofocus.
You need an f2.8 lens to autofocus with the 2xTC's on the dRebels.

Fran