That's not how it works. You don't need your bank account tied to your Paypal account. The Paypal account holds money itself. He just hasn't paid yet. Don't worry :) 

Oh ok, I wasn't sure. I thought maybe it wouldn't let him pay. But I guess he's just waiting to pay.  I'm kind of brand new to the selling on eBay thing. 

Holy fuck. On top of those prices, their batteries should have ran out by now (at at least very soon). That may be the greatest rip-off I've ever seen.

I didn't even know about the whole battery issue until earlier this year. My battery for Pokemon Blue is probably goin to run out soon.

Make sure to have communications with your buyer. Thank them for the purchase, remind them of payment due in polite terms.

Definitely get your paypal confirmed to bank. Makes you look more legit. Have to keep in mind this buyer is giving you $50 with nothing in hand at first. That's a risk.

What happens if he forgets to pay for it?

You can relist for no extra money and then even report him as a non-payer. But, I have yet to have someone never pay. Usually a polite reminder is more than enough.

First, make sure your Paypal account is set up, or the buyer cannot pay. After you have your account, keep good communication with your buyer in order to explain things (you're new to eBay, just got Paypal, etc.). Politely ask when you can expect their payment, then assuming they pay shortly after make sure to ship your items immediately. After they receive the package and check things out, communicate again in order to exchange positive feedback. Positive feedback shows people that look at your future items that your previous buyers had a good experience. This is very important.

The next time you go through eBay to sell something like this, it may be a better idea to sell with a "Best Offer" price. It's essentially a "Buy It Now", but it gives buyers an option to offer something lower, just in case you're willing to bargain. So in the case of your DS Lite, you could have posted a $99 price with a Best Offer option, and maybe had someone offer more than $50 for it. Just something to consider for next time, and I hope your current transaction goes smoothly.