For an extra 10 lb. and additional ~$100 you can choose either a 4, 5 or 6HP Tohatsu over a 3.5HP Tohatsu. The 4, 5, 6 HPs are the same engines, just different carb set-ups.

A 6HP usually can make a 10ft. inflatable plane with just one 180lb. person onboard.

Tohatsu is making at least the powerheads for most other brands, most times the only change/difference is the 'cosmetics'.

FWIW - The best prices Ive found on the 'internet' is internetoutboards.com, usually free shipping. http://www.internetoutboards.com/product_list.asp?id=88