Vinyl Inventory to Start With?

631 is for wall words or temporary signs, it has water based glue. I wouldn't recommend getting any of that unless you are planning on offering them to customers, which if you are clear tape is not what you would use for it. Also I would not get 50 yds. of black and I'm not sure if I'd start with that much white either. I buy mine in 24" by 50 yds of white, but I'm pretty established and it still takes me awhile to go through it, granted I try to steer everyone to printed now though.

Dunno exactly what your Two Color Banner Starter Kit 6 Colors 24"x5 is so I can't comment on that. Cast I wouldn't even worry about right now, another thing is to try to get a local distributor, they can really help you out.

I would get whatever local schools colors are and use them with a white base for window decals, because parents are always wanting their kids sport decals for their car windows.

Oracal 651 is "calendered". The way calendered vinyl is made, it has "memory" and may shrink (causing white edges on darker colors), and is usually made with lower quality polymers and adhesives. The cheaper calendered vinyls, especially in-house or no-name stuff off eBay, simply won't last for anything more than a short term sign, such as advertising a local art fest or charity car wash.

Oracal 651 is higher quality than most calendered vinyls. I recently posted a thread showing 651 after a year in Florida weather on a metal building, which is certainly a very severe install location (much more temperature shifting than on a glass window of a normal storefront, and no overhang at all). Not even 651 will install properly on anything more than a gentle curve (such as a rear car window) or over a rivet.

http://www.t-shirtforums.com/vinyl-signs-decals/t188488.html

Oracal 751 is "cast" vinyl. Cast vinyl generally will not shrink, is usually made with higher quality polymer and often has a different adhesive than calendered vinyl has. It can be applied to sharper curves and will conform over rivets if you are lettering a box truck, etc. 751 is the "lowest" level of cast. Oracal's website will give you the lifetime rating for each type, 651 is actually quite high for calendered, 6 years, 751 is 8 years. Black/white, transparents, and metallics often have different lifetime ratings than the rest of the vinyl in the same class.

You will want to look up reviews of whatever vinyl you are using. There are other brands, like 3M, LG, Arlon, and Avery. Some of these have a bad reputation for mistakes the manufacturers have made in the past. 651 came up the most when I researched what vinyl to get as far as quality vs price, but I plan on doing more small custom novelty decals than serious branding lettering and graphics on a company's fleet of vehicles. A lot of places consider it unprofessional to use any calendered vinyl for that, but I am quite impressed with 651 so far.