I've got a QCTP on my machine, so it's a given I think they're certainly a good upgrade, but I used the old lantern tool posts and Armstrong tool holders that came with it for many of my projects and they worked well enough. The QCTP is a great timesaver, but there is something (not always something nice!) to be said about learning with older/simpler tech.
I would recommend a QCTP, but IMO if you are trying to fit things into a budget, the QCTP can wait a little while....you'll get tired of swapping tools soon enough to sell yourself on it but it isn't going to allow you to do things you can't otherwise.
The only other advice I can give is to buy as you need instead of buying what you *think* you might use someday. By the time you need the do-dad (assuming you ever do) you might have found another way to do it with what you have on hand already or may have outrown the lathe you have. Apply cash to what you need to finish the projects you have and build up tooling as your projects require it.
I look forward to seeing what you can make the 7x12 do.