theres a piece of advice an experienced costumer & prop maker once told me -
there are 2 major factors in prop making - time, price and look/accuracy. You can once ever achieve 2 of these at a time. SO have a think.
so if you want to limit the price - you are gonna want to really read as many stickies as you can so you can get the look and accuracy right (esp.ly if you want movie quality). plus expect to have to go learn up the skills that you may have to learn. these include working with resin, fibgrlass, casting resin.
Oh and expect to spend oooodles of time to get it right.
thres lots of stickies here and on the internet. the one thing I finally realised is that there often isnt one Right Way of doign stuff, thers gonna be lots of trial and error. good luck and I am sure lots on this board will be here to answer any of your questions!
Nate