APC. Best brand I know of.
Look for something that gives you enough power for all your devices for the time you need.
I have a 3-4 year old 1300 VA APC and it can power my computer for 25 mins or so at full load (ie gaming). Desktop usage probably 50 mins or so. Most people only need 5 or 10 mins to shut down their computer properly, but I went overboard and I don't regret it. This model gives me lots of useful info.
The good thing about a good UPS is that when it doesn't perform well anymore you can replace the internal battery, which is very much like a car battery, and keep using it. This is a long term investment.
Regarding price, i suppose it varies by region but if you want a really good one you might be looking at least at a $100 purchase, possibly more depending on your needs.
For instance, this is the successor to the one I have and it's currently priced at around $150 with a discount:
http://www.newegg.com/Product/Product.aspx?Item=N82E16842101421