do you have access to Adv. Vault 1?
In it, they have two things specifically up your alley.
1) Magical ammunition (though, i have to say, the prices on it are kind of steep) (note that even ammunition that is described as a bolt could still be used for an arrow, and visa versa)
2) For -some- alchemical items, they give a modification that you can use to attach it to ranged ammuinition (usually in the form of an increased cost); though, when used this way, you don't use your own powers or attach modifiers, but instead use the alchemical items attack modifier.