I need some engine advice!

Alright. So my luxury 2000 Mazda 626's engine seized up to my own ignorance with the oil. I can either try and purchase something for about 3500 or change the engine with a Jasper's engine for 1600 (This is in US dollars). The new engine is warranted for a full year along with the work to put it in. Which do you think I should do? ... Also, my car has a new transmission in it.