I have seen P88 mags advertised at CDNN, and as of this moment they show 10 rd factory compact mags for $9.99, but out of stock. You can give them a call to check (800-588-9500) since sometimes what they have may not be in their catalog or website (www.cdnnsports.com)
I believe it was only the "factory banner", Walther P88 C (compact) 10 rnd. mag. that CDNN has been offering for sale in their recent catalogs for $9.99- (and not a P 88 mag). They were also advertising the mag as fitting the P 99, (although not flush).
I bought one for my P88 C from CDNN. It is a Walther "factory" mag (I guess) but it is made for Walther by Mec-Gar and has a black plastic base. I hope they get more- I would like "more".
If you're interested in "other" after market mags for Walther- I notice that www.GunAccessories.com is selling: ProMag, Mec-Gar, "Factory", and "Imported" mags for Walther pistols including the-
P22, P38, P88, P88 C, P99, PPK, PPKS & PP- in all the capacities and calibers including the .32 acp.
For the P88 C, GunAccessories lists a, 9mm 32 round blued steel ProMag for $34.95. ...Hmmm?
AFAIK, Mecgar IS the OEM magazine manufacturer for Walther. Both of the 10rnd mags for my P88C are marked Mecgar as well as all my P99 mags. Both my P88C mags have the plastic floorplate, the gun is datemarked KK (1988). Also, both P88C mags work in my P99's as do both my P88 mags(but they stick out a 1/4").