I think there are a few things you need to take into account - Rick pickups are single coil, have pole pieces directly under the strings (rather than smaller ones either side) and are mounted hanging from the pickguard/surround, rather than screwed to the body. You'll get closer the more of these things you do. They're also floating above a maple through-neck, which provides some of the clarity.
I did an experiment recently to see if I could get a Thunderbird to sound more like a Rick, with single coil pickups mounted from pickguard rings. Answer - yes. It sounds a lot more like a Rick (but not all the way). [url="http://basschat.co.uk/index.php?showtopic=53048"]http://basschat.co.uk/index.php?showtopic=53048[/url]
If you want a cheap first step, I'd start with Quarter Pounders, and see if you like them. Dark Stars are a very expensive experiment!