HAPPY BIRTHDAY!
I'm certain there is a middle road here. I also do not often buy things for myself and almost need to be pinned down to do it. But my local pfaff dealer is wonderful. So let's think what she would do for me in this sistuation, and let's see if it helps you.
(this is all standard stuff no specail favors or anything like that)
TRADE IN, what is the trade in value of what you have towards a new machine, and might you get more "trade in money" if you were buying a fancier machine?
TRADE UP, if you buy a bottom of the line Pfaff at my local store you can trade it up anytime in the next 6 months (or maybe it's a year) and get the same exact money you paid to trade up.
TRADED IN perhaps they have a machine that has been checked over by their staff that someone used to trade up for, that you can have for less money. When the old tradeup machines sell again they sell for 1/2 the money.
Now I looked at the Pfaff 1122 (oh please other members don't smite me down!!!) It's the bottom of the Hobby line which means it's the bottom of the Pfaff line, I considered that route myself... I instead bought a bottom of the line of a different big name brand 4 months ago, and now I want something better with more gagets, even if that means getting an older machine that has the bells. You and your skills will fill the shoes of the sewing machine you're considering in about a nano second, and then you'll have a nice little machine that will last forever, all the while you're wishing you'd gotten the 1142 with the automatic button hole or that one fancy stitch that you never thought you'd use, but it sure would be great to help quilt this project. And you'd still be stuck with whatever bill or dept that you would have liked to get off your back.
You've been using your machine for sometime now, and while it isn't perfect, you know all of it's stupid things and the tricks to fix them. Is it better to save half for a better sewing machine in a little while, and pay down the other stuff a bit? That way you know you'll get it just not right this minute, and you'll have a little padding if you need it for something unexpected up ahead.
Advice is what we ask for when we know the answer and wish we didn't...