Hi Chance,
Everyone's level of "good" pricing varies. What's good to you for all of those types of vinyl may not be to me.
The one great way to know what's good is to learn what the cost is in the market for those various vinyls, as they range in price. As well, there are a lot of variations and brands of each vinyl type you've mentioned. You will need to learn which products you want to use out of all that's available.
To help you learn market prices of apparel/heat applied, sign and decal vinyl, visit these sites as they sell all of these vinyl types:
-Beacon Graphics
-Specialty Graphics
-SignWarehouse
Also, keep in mind that you may not find a Wal-Mart of vinyl just depending on what you actually need or desire to use. It's also a good practice for you to set up accounts at more than one supplier, as you may have to go to the backup supplier if your primary is out of product. Just makes sense.
When you search more on this forum, I'm sure you'll find some other suppliers too.
Hope this helps!