Factory mag capacitys for P228's.
10rd mags made by Mecgar. Blah, due to capacity. $10 is all I'd pay for one.
13rd mags made by SigSauer. Cool. $20 used in good condition, $30 NIB.
15rd mags for P226's made by SigSauer. Cool, but don't fit flush. Freeds Desgins makes a collar that goes over the floorplate to give it a flush fit look, which is nice. $30 NIB, the collars are available from Brownells, and are kinda pricey($12 ea I think??)
20rd SWAT mag by SigSauer. NOT flush at all, definte cool factor. $45-$50
Aftermarket mags for P228's.
13rd Promag. Ugh. Waste of money. <$10. Don't buy.
15rd flush fits by Mecgar. The best of the best. $20. Buy lots.
17rd P226 mags from Mecgar. With the Freeds X-Grip collar, pretty cool. Also $20.
Mecgar makes most of Sigarms factory mags nowadays. Shiny blue mags with 'Made in Italy' on them, with a smooth back, are Mecgar. Flat black parkerized mags with a dovetailed or 'zipper' back are SigSauer german made mags. Both are equally good.
Helpful hint. If you somehow get stuck with 'ban mags' that only hold 10 rounds, swapping the follower from those mags into normal capacity SigSauer mags will add a +2 capacity to the mags. This doesn't work with Mecgar mags, but it does with P228 13rd SigSauer mags, 15rd P226 SigSauer mags, and 20rd P226/P228 SigSauer mags.