I put an order together with Seedsman a couple weeks ago; got my total, went to Coinbase to make my Bitcoin buy, and realized it would be a week before the money would be in my account -- bummer. I rounded up to the nearest .001 BTC, figuring if prices changed I'd have a little wiggle room. When I got the notification I could access the money, I recreated my order (except for something that was out of stock so I got something else) and bought my seeds. I ended up with more than my original order and had about 95 cents (equivalent) left over because my BTC had appreciated about six bucks in the week between buying them and when I checked out with my seeds. One week later that 95 cents is now a whopping dollar-nine. Who knows how much it'll be worth by the time I need more seeds?!
Over all it was a bit of a hassle but with the discount and bonus seeds, it was totally worth it. Next time I will probably pay the extra and buy BTC with a credit card, I think that's available right away iirc.