Inexpensive MM Cartridge

Hi All.  I'm helping a friend who has a late 1970's Pioneer PL12 turntable. The manual TT is in good working order, bearing and motor lubed, etc. We need a MM cartridge to mount on the stock S-shaped tonearm.  Budget is up to around $300.  Suggestions please!  Thanks, and Happy Holidays!
@mwinkc - thanks for your encouragement.  I am hopeful.

@jrpnde - I would agree that there are some advantages to pre-matched cartridges and arms.  Not that I trust the manufacturer's to provide the best sounding cartridge (there is a bottom line to protect, after all) - but I do expect that the cartridge compliance will properly match the arm effective match, and (if there is no VTA adjustment) the cartridge will match the required VTA.  There is no VTA adjustment on my TT, nor did I know the effective mass of the arm to match the compliance (hope I didn't shoot myself in the foot there).  But I think it's also possible that the cartridge I purchase will exceed the stock, and I do know how to set up a cartridge (despite my transgression above).  We shall see....
Update: it's pretty much impossible to find effective mass value for the Pioneer PL-512 S-tube tonearm. The  Nagaoka MP-200 seems to be a low compliance cartridge (though I read that Japanese specs for dynamic compliance are taken at 100hz rather than the required 10hz - the whole things is a spaghetti mess!).  I can always use a test record to determine resonance frequencies and if I need to increase the tonearm mass use some blue tack to optimize and then order a heavier headshell to increase the effective mass.
I have owned quite a few entry level vintage TT's. I find that the old AT cartridge format works well with the heavier S shaped tonearms. I had an older 440 OCC body with a newer ML stylus mounted on a similar Technics TT (to the Pioneer 512). I think these carts were developed around the same time as the Pioneer and mat have been used as the reference. 

Audio-Technica with MicroLine stylus is definitely better than any Nagaoka with Elliptical tip. Also AT is fairly mid compliance, Nagaoka compliance is too low for MM and this is strange. However, you can use heavier headshell is your tonearm counterweight can work with higher mass. 
Chakster, he bought the Nagaoka. be happy for him instead of your usual BS about cartridge choices of what is good and what is not.