"I'm mainly looking for a cheep sound card that would give me close to no latency." Cakealex has given you the best advice.
What you need are good audio drivers. That is what Sonar needs to work properly, that is the heart of a good audio DAW system. Generic audio drivers are for the most part a big waist of time.
So your goal is to by an Audio Interface that comes with good drivers. Focusrite Scarlett's have become the most popular in the lower price point market for that reason. There will be a bunch of others at that price point but at this time I'm not aware of any with as good a rep as the Focusrite Scarletts.
Example: Musicians Friends Stupid deal of the day was a Tascam interface for $50 and to look at the specs would be identical to the 2i2. But this was the catch-
'Class compliant device does not need drivers' !! So sure, it will probably work fine with a Mac and with some audio apps like Audacity, but I guarantee you big problems with Sonar. USB mikes fall under this category too. People spend day's and day fighting these set ups when the answer is simple- proven, tested ASIO drivers.
Almost all modern audio interfaces use direct monitoring so there is no latency while overdubing. This is nothing to do with Round Trip Latency which is a whole other kettle of fish.
Interfaces with lower round trip latency performance are not cheap.