Aside from that, two other places you can try though (so as to broaden your options) would be:
1) Auctions (i.e. Yahoo Japan, ebay, etc.)
You'd be able to find a few people selling these stuff there
2) Hit Style Limited (Hit-Style Ltd.)
They are THE official distributor of Sanwa products in Hong Kong and Macau (aside from being a Konami arcade official distributor themselves). Hit them an e-mail
That's pretty much it (but go for DJ DAO as your first/primary option).
P.S.
I could have recommended Himuragames.com to you (if you asked this question two years ago). Right now though, the site seems to be down and their not taking orders (used to get a bit of my Sanwa stuff from them a few years back).....
the omrons in the konami ascs are v-10-1a4 but dont worry about getting the exact same switch
there are many variations on the switch where the differences are as small as the style of the connector lines and such so it isnt essential to get the exact same switch as in a konami asc or an arcade machine
I've already had to order enough products from DAO to know that its incredibly overpriced. The shipping is through the roof! Thanks for the suggestions guys