if it hasn't already been mentioned, first thing off the bat is to find the spacing of your rear dropouts. they may be 126mm or 130, or possibly even 135mm. this will determine much of what is possible WRT economy. if 126mm, new pre-built wheels and even new hubs may not be so easy to find. not that they aren't available. so if 130mm or 135mm you shouldn't have any trouble finding pre-built wheels anywhere from 150 on up. or you could build them yourself from readily available parts you can find online along with a little guidance from youtube videos and websites.

have fun.