You can prolong the life of a moderately crappy wheel by ensuring sufficient tension. If the tension is evenly distributed, the wheel is likely to last much longer. But when spokes start to pop, this type of measure isn't going to help.
I see some reasonable priced wheels with Sunrims CR-18, DT spokes and basic shimano hubs that I suspect could last a while... something like this 27inc rim
http://www.universalcycles.com/shopp...s.php?id=51189