A 1.5 gallon pot is going to limit you badly, unless you are making 1 gallon batches. I think the easiest thing to do in order to advance on is to start building your own kits based on the recipes out there. Try downloading BeerSmith or ProMash and look through the recipes in them. They will let you scale the recipe to what you can do. Or look up Cat's Meow 3 and check the recipes in there. Or try the BeerTools.com website. Just pick a recipe and try it. I would highly recommend doing a partial mash (soaking the grains in a bag while the water simmers, then removing it). You can also switch the hops a little - if you make a batch and think you'd like to try a hoppier version of it, just throw a few more hops into it. Or for hop flavor, throw some more in at 10 minutes. For aroma, throw in some hops at the every end of the boil.
But I would be looking for a bigger pot - perhaps you can borrow one from somebody. These need not be expensive pots - I have been using a cheap aluminum pot that came with a turkey cooker for a couple of years now. I got the turkey cooker with pot and other stuff for $30.00 when it was on special at amazon (and got free shipping :).
As long as you care for an aluminum pot, it'll work perfect. Don't use abrasives on it or abrasive pads. Just clean it up with a cloth and dish soap and let it darken as it ages. The dark stuff is aluminum oxide which is harder than the aluminum itself. When I got my second aluminium pot a while ago, I "seasoned" it before using it for beer by cleaning it, then boiling about a half-gallon of water in it for a while with the lid on. Dump, boil another half gallon, dump, let dry.
And when you are able to get into all grain, I'd go with the batch-sparge method - it's cheap and easy.
--Jeff