Go into a suit shop here and get them to measure you before you buy. Just say you need the measurements for a suit being bought abroad for you or something. Most people reckon their inside leg is longer than it actually is. ie. if you reckon you're a 32" in jeans then you're probably only 29.5" or 30" in slacks.
They were perfectly innocent remarks! Roxy and I are both ladies....'get a room'..I think you've been listening to Twink for too long!
Anyway, buying a suit online ....I agree with Roxy. Personally I'd have reservations about quality, sizes etc. The hassle of having to return it if it's not right and the expense of the postage. Don't think they pay for it if you're dissatisfied.
You might find that your measurements are different slightly for different brands etc, so you could end up with something a little bit off size, or else purchase online a suit brand that you have already and hope the measurements are the same.
See what type of returns policy they have.