GrassStrip - I'd get one, and heres why.
I too am a low time PPL - about the same as you. I learnt in well equipped 172's with the full panel and moving map GPS. It was there on the panel in front of me, yet I don't think I once referred to the GPS when learning, save for a couple of times when I worked out my position using DR and then glanced at the GPS to see how accurate or otherwise I was. It was, however, there if I needed it.
Lets assume a scenario. You fly to A, but on the way get lost. The wind wasn't as forecast, something wasn't set right, or a gross error was made in planning (shouldn't happen, but it can, and we're all human and susceptible to mistakes). Whatever the reason you end up a way away from where you expect to be. You try looking for features - but still you're not sure. All the while, as a relatively inexperienced PPL, your workload is gradually creeping up, as the pressure on you to find out where you are grows. Now I know you have a number of ways to work out where you are, use radio aids (if you have them), get a QDM from whoever, or even call 121.5 for a position fix. It is essential that you are happy with doing any of the above. To me, though, calling D&D is less preferrable than pulling a GPS out of your bag and using it to find out where you are. Of course, if the GPS is kaput, or the satellites have all been knocked out by a solar flare then it ain't gonna help you much, but the likelyhood of that happening is somewhat less than you being able to say OK - the GPS says I'm here, the map features vs. what I can see confirm it, and I see now where I went wrong - wind must be X instead of Y, or my last turning should have been Z, oops I misread that 1 as a 7 etc. GPS back in bag, on seat, whereever. Workload reduces, and the likelyhood of errors compounding and making a bad situation worse lessens too.
You, like me, enjoy the challenge of DR nav. If you are the sort who likes this, then the fact that you have GPS in your arsenal won't change your basic instinct to navigate using all your senses and tools - unless you let it. it is just a matter of discipline. The continuing GPS/No GPS debate reminds me of the old driving adage - that if you wanted to ensure safe driving, sticking a 6-inch spike in the middle of the steering wheel would certainly make people drive more carefully. Now we've got seatbelts and airbags and ABS, and yes, a lot of people still drive like complete ****'s, but there are drivers out there who stilll take care. Use all the tools at your disposal to ensure safe, enjoyable flying, and used them wisely and appropriately. GPS is a tool like any other, and never should be a crutch.
IMHO, YMMV etc etc...
JP