Megs,
Just remember, what goes around comes around. My dear sweet wife has been buying me stuff for deer hunting for years. Lacross boots, Browning knifes, Game Camera' s, tree stands, guns, ground blinds; all were wonderful gifts. You don' t have to spend much to make a hunter happy, just knowing a wife supports his hunting habit is enough.
Megs formula1 said it all with that statement, I am in a quandry as to whether a gift certificate would be to impersonal or not. To be honest it depends upon him, I for one would be ecstatic if my wife got me one even if it was only for $20!
One advantage of a gift certificate is it will allow him to get exactly what he wants, with so many items that are a personal choice as far as bow hunting goes I would say the gift certificate is the best.