You may want to check this out. Comes with the aluminum spool included. Also, you can weld with gas or flux core. Looks like it's on sale right now.
I have one and it works well. I know some guys dont like Eastwood products, but I outfitted my shop with their gear and I only had an issue with 1 thing, an orbital palm sander. So far everything is performing well, been about a year and a half.
Eastwood MIG 175 Aluminum Welder with Spool Gun