What are some good replacement P-bass style pickups that would sound similar to a Rickenbacker? By that I mean powerful treble an extreme punch.
Quarter Pounder seems to be the best drop in replacement, the only real way to get a Ric sound is to buy a Ric tbh, but the quarter pounders are very treble-ey and punchy
I am on a similar quest, though I am trying to do it on the cheap. For me, I am gutting a squier P bass and redoing it as something of a hybrid. I am using a brass nut, and installing a second P pickup in the bridge section and wiring up independant tones and volumes for each. from the obscure internet opinions I've read and my hunch, this might be a good way to get a multitude of sounds including that of the ric, My only suggestion is reversing the bridge P so its not to brittle on the treble side
A single P pickup is not gonna get a Ric tone.

If you want more trebble, you're just as good getting it with your amp or pedal EQ. The placement of the P pickup is just not conducive to 'the Ric tone'.

If a Ric isn't in your budget... the BEST alternative is to look for a used Peavey T-40. They were made from the late 70's to early 80's. They're made in the US and built like tanks. On top of that, they're VERY versitile and their two humbuckers can be switched between single coil and humbucking mode. Their only drawback is that they weigh about a ton. They're also rather 'hip' these days, and being snatched up on Ebay after intense bidding. They SHOULD be going for about $350... but it's not uncommon to see them go for $500. You may also get a good score and find one on Craigslist as low as $150. Check out this video that directly compairs a Ric to a T40: http://www.youtube.com/watch?v=PjwHFHDz_Hg

Also... there ARE Ric copies out there. The best are the Japanese copies made during the "lawsuit era" in the 70s. The best were Ibanez, Greco, Hondo, and Tokai. They are pretty hard to find though, as Rickenbacker takes them down whenever they pop up on Ebay. Because of this rarity issue, they tend to be pricy... but still less than a real Ric... about $800-$1000.

Finally, there are contemporary Ric copies too... but i can't post any links. But i know German, Chinese and Korean manufacturers that do Ric copies...

So yeah, TL;DR... love the P bass for what it is, and look elswhere for a ric sound.

I remember when I wanted a Ric... but then i actually played one...
"Punk Rock should mean freedom, liking and accepting anything that you like, as sloppy as you want, as long as it's good and has passion."
Quote by Din of Win
I remember when I wanted a Ric... but then i actually played one...

Every time I lust for a Rick I just look at the price tag.