You can use whatever you use on your other roses. A balanced 10-10-10 fertilizer won't hurt, Osmokote or a similar time-release is fine, as are mostly organic fertilizers (Espoma Rose Tone, Mills Magic Mix, whatever organic stuff is available locally). If you need the epsom salts, a soil test will tell you, most soils don't need it. You don't need fancy "rose food" fertilizers.

Cost effective is really important to me, I just recently tried tea on my other indoors. I'm one of those indoor potteds with the mini - at least until the spring. I'm kind of concerned that it's using up whatever it is in the pot that is making it grow though.

I have literally no chemical knowledge when it comes to plants, and a very basic sense of cause anf effect...

The outdoor ones growing has been an equal miracle to the indoor, since I jumped into gardening with both feet this last summer, and spent the last 6mo in a mad rush to get everything growint and established while praying the frost would hold out - another day, another if possible.

Since the frost has hit, I've had to obsess solely over my indoor plants.

Well, a basic primer on fertilizers, and what all those numbers mean might help, here are some articles from the ARS that can help.

Don't go overboard trying everything you see on the forums, though. If you want to try something, I recommend doing it on a smaller scale, just to see how your plants react.

Here is a link that might be useful: Fertilizing Roses page from the American Rose Society