H'okay, I'm home, now. It seems like I can confirm that you can immediately use the money once you load it up to your PayPal Account.
I think I need to clarify something before people get confused:
You need to buy this for it to work for you:
Do not go for the Mastercard version. (Unless you want to, I unno. It's up to you!)
I don't think this picture gives it much justice, but the minimum amount is $20 USD, while the max is $500 USD, plus a $3.95 USD Purchase Fee. (I live in New York City.) Which isn't so bad, in my opinion. I use Gift Cards all the time to pay for gaming services.
Anyway, once you load it in, it's available for you to use:
I found this card at my local 7-11 store. I tried going to CVS and Walgreens, but to no avail.