If you only have the blue smoke on startup, and not any when just sitting in the driveway/garage and idling when all warmed up, then you likely do not have any problems in the block area. So I wouldn't be looking at replacing the entire engine then.
Timing belts on a 94 5S-FE engine should be replaced every 60k miles. If you are at that point (or beyond), you will want to do a major maintenance job on the engine (timing belt, water pump, new oil seals at the front of the engine, idler/tensioner pulleys, etc.). When you go in to do that, really there isn't that much more extra work to remove the cylinder head from the car, get a good gasket kit for a cylinder head rebuild, take the cylinder head to a machine shop with the new valve seals from the gasket kit, and have them machine the head gasket mating surface, check valve lash, and put the new valve seals in. Then, with a new head gasket and new head bolts, and gaskets from your gasket kit, start putting everything back together again. This will cost you less than getting a decent engine.
Otherwise, a good used engine will liekly cost around $500. But you will probably want to do all this work on a used engine also, to make sure it doesn't do the same thing your current engine is doing after it is installed.