Super Cheap ebay batteries + Inno Mag case?

[gurachn]

I have just ordered an x51v and its clear I am going to need some extra batts.
I also really like the Innopocket Magnum case so it looks like I am going to have to go standard size rather than extended.

There is a company on ebay called "Pointing mouse" in Hong Kong that has batteries going for $4.99!
http://cgi.ebay.com/For-DELL-AXIM-Ba...QQcmdZViewItem

They have a 98.5 +rating and over 65k of feedback, so its obviously not a fly-by-night outfit.

My first question is has anybody bought from these guys before or from similar?
For this price I figure I can buy a few and swap em out.

My second question on this is for those of you using the Innopocket Mag, is it such a snug fit that regular battery swapping will be a pain?

Any thoughts on this appreciated