I'm slanting this article towards AR furniture. The AR platform allows a truly ridiculous level of accessorizing, and my primary interest lies in having rifles with different ergonomics than totally standard, just to get a taste for different feels.
I've found that the rule of thumb is that whether you're looking at a fixed or telescoping stock, you generally don't want a stock that costs less than $50. $60 is where the reliable stocks seem to hover. Although you can get buttstock assemblies really cheap, the buffer tube + recoil buffer tend to zing you if you get a deal on the buttstock assembly. Package deals tend to save you money over an a la carte order.
Rock River Arms's "Tactical LE Entry" stock is a big hit with my wife. It's light, and about the same length as a collapsible M4 style stock at its shortest setting (which she seems to prefer). Because it's a fixed stock, California doesn't consider it an 'evil feature', so it doesn't prevent the use of detachable magazines!
JP Precision sells a number of different AR stocks. Regrettably, they seem to have discontinued their beautiful wooden thumbhole stocks for the AR.
TangoDown offers the Battlegrip pistol grip, the Vertical Battlegrip, and the Rail grip. These products are available in four colors: olive drab, flat dark earth, foliage green, and black. TangoDown grips have an agressive texture and the quality of the product is second to none. Both the Battlegrip and Vertical Battlegrip have an internal waterproof storage compartment perfect for storing extra batteries for your optics.