Whether you have a 4ft strip light or 2 24" hoods, I think either way you can retrofit a 2x55w kit from
http://www.ahsupply.com into them. The 2x55w kits are about $65 plus shipping. You'd have to follow the diagrams and do it yourself, but I've heard its not that difficult. You will have to take the "guts" out of your current strip/hoods (ballast, reflector, etc...) and replace with the CF kit. Thats probably the cheapest you are going to get, but there is some work involved.
I'm a big fan of Coralife fixtures.
Hellolights.com is a good place to buy them and usually has the best prices. They have a 4ft 2x65w fixture for $125 plus tax, which is over your stated price range. Its my experience that Coralife fixtures last years and they are reliable. It would be a good investment IMO and would allow you to grow alot more plants then you can now.
HTH!