i use ambroid for everything i do plastic wise. i think its the best stuff out there. you can use multiple layers and still its paper thin!!! i use it on my figures...never need to fill gaps nothing. if you want a good opinion...you'll never go back to anything else as far as im concerned!!!
as far as "wasting money"...it'll last you a long time and many many projects if you keep it closed tight. no...i think you'd be wrong not to spend the $$$ on it!! up 2 u though.