how much would it cost to do a complete clutch switch from daul mast to single for a 03 tiburon?

Its pretty much the same cost as for a clutch replacement. The only difference is that you'll have to spend about $500 more to buy the flywheel

So... you might be looking around $1400 to $1600 to convert from dual mass flywheel to conventional clutch system. It depends on the shop rate in your area. Some charges more or some will charge less in labor. The key is to find a shop to negotiate fro a good labor price.