I've never heard about Lion Battery INC. before but at least they have some interesting HTC Magician (i-mate JA, O2 Xda mini, T-Mobile compact) batteries in stock - with enhanced capacity!
While the original Magician battery is 1200 mAh only, the Lion Batteries are available in a 1550 and 2000 mAh version. The 1550 mAh battery has the same size of the original battery, the 2000 mAh battery is "slightly" thicker and requires a new battery plate but I have no clue where to get it from or if it is part of the delivery:
The 1550 mAh battery is available for 54.95 US$ while the 2000 mAh version costs 94.95 US$. According to Lion Battery, both batteries are in stock.
Last but not least they also have batteries for other PDAs in stock, might be worth to check if you need a new/enhanced one.
Cheers ~ Arne