I'm looking to make some handpours for the first time and was hoping to get some suggestions on where to get the plastic. All help would be greatly appreciated.

I have poured soft plastics for 10 years or so.  I have tried every type of plastic out there and I always kept going back to M-F Super Soft.  Do a search for M-F plastic and it will pop up.  This is just my opinion, as others will have different preferences such as L.C., and Calhoun's to name a couple.  My suggestion is to try out different types in the pint size and then order in a 5 gallon size once you decide which is best suited for you.  Shipping is pretty high on this stuff, but it is a great hobby.