Tweaking my new Rega P1: How much is too much?

I started down the path of this little "hobby" (what a pleasant euphamism... sounds SO much better than "addiction," doesn't it?) several years ago, but within the past 2 years or so it's definitely picked up a lot of steam. I recently relocated from DC to the Tampa Bay area, the cost of living is lower, I've got more space for toys, and overall am better off financially than I was a few years ago.

I had been thinking about making the plunge into analog for a while but was putting it off for various reasons, one of which was that I knew there was about a 100% chance that I'd get hooked and start wanting to tweak and upgrade everything, and it's just WAY too easy to to blow gobs of money on analog/TT tweaks and upgrades ("oh, it's just a new cartridge... it only weighs a few grams for cryin' out loud, what's the big deal?") and it'd just get out of hand.

Well, hence this post :) I saw a Rega P1 demo unit pop up on audioadvisor a couple weeks ago, so I figured what the heck.

First off, let me just say that even though my previous experience with turntables was limited to a couple "kid records" I played on my parent's record player when I was 5 and a brief foray into the DJ/spinning side of vinyl that this just seems like a great starter table. Comes with everything you need, great price tag, and, of course, very tweakable.

Therein lies the problem... the glass platter upgrade seemed like a no-brainer, so I've already got one of those. I also have a Shure M97xe on the way as it was inexpensive and I wanted to get some hands-on experience setting up a new cartridge to see how it affected the sound, but just as much simply because I get almost as much out of the "hands on" aspect of the hobby as I do actually listening to or viewing the end results.

And, again, having no relevant prior exposure to the wonderful world of analog, I can already tell I don't really like the RB100 tonearm that comes with the P1. For the price, I'm really in no position to complain, but it just "feels cheap" to me, the counterweight is very clunky, the wiring is cheap, no VTA, etc.

Now, I recently just came into a nontrivial amount of extra cash, most of which is getting hidden away where I can't find it for obvious reasons, but it does leave me with a decent chunk of money for some new toys.

I'm going to primarily be performing a major upgrade to the rest of my rig first, but I'm sure some of the funding will be applied to tweaking the analog side.

My question (I can just hear anyone who has actually read this far shouting "FINALLY!" :) ) is: at what point should I start thinking about just replacing the P1 with something else, as opposed to tweaking it? I mean, let's say I throw an upgraded Origin Live tonearm onto it, maybe buy a nicer cartridge once I inevitably decide that I could "just use a little more" out of it once I upgrade my speakers/etc... when am I likely to run into a point of diminishing returns and need a higher-end TT to keep going?

Like I said, I derive a good portion of my overall enjoyment from all the hands-on stuff (of which there is a lot when you're dealing with analog) as I do from actually using it, and I figure given my noobness on this side of things, probably far better to risk screwing up a P1 I got for $350 than something I blew a few $K on. That being said, even I have to appreciate the silliness of sinking money into tweaking the P1 only to find out that it would have been far easier and cheaper to have just picked up a nicer TT from the start.

A lot of this really boils down to me just needing to spend some more quality time with my ears and deciding what bits and pieces are most important to me, but I can't imagine that I'm the only one who reads these forums that has found themselves in this situation, and I would very much appreciate any opinions/advice/commiserations/etc. anyone felt like offering :).

If you've made it this far, thanks for your time :)
If you like the Rega sound I suggest buying a P3-24 with the optional power supply. You'll get a better table and arm that will significantly outperform the P1 no matter how it is upgraded.
Second Narrod's comment. With the Shure you have a respectable entry deck and reached the point of diminishing returns. The P3 has one of the best "bargains" in arms. The new PSU means the P3 is one of the most stable of bases.

I'd say enjoy the P1 for a year, save your shekels, won, lyra, or pounds and go for a big brother deck later - that is if you like the Rega sound.
Save the glass platter and cartridge and get a new Rega P2 to put 'em on. Much more tweakable than the P1 with the aftermarket stuff and still quite a bit cheaper than the P3. If you love it and tweak it with a subplatter, counterweight, etc., you can always transfer those to a P3 down the road. Or just get the new P3-24. Depends on how many incremental steps you want to make and if you enjoy tweaking...
I agree with the other posters. Definitely do not put any more money into that table. Sell it and purchase a Rega deck higher up the line.