Figures should be easy - the only known repro figure that is anyway close to the original is the Stormtrooper (known as the Poontrooper) - there are a couple more - mainly Boba Fett, Yak Face and the Blue Snaggletooth but all are pretty obvious
Weapons are not so easy - an eBay is full of them - especially in 'childhood collections' - best place to check is the imperialgunnery.com - there are some great pictures on there and tips as to what to look for