What is your Apple iPhone 4S worth now?

The wait is finally over.

With Apple's unveiling this week of the iPhone 5, iPhone fans can expect a 4-inch display with a 1,136 x 640-pixel resolution, an A6 processor and 4G LTE speeds in the "world's thinnest smartphone."

But the $199 (16GB), $299 (32GB) and $399 (64GB) price tags may difficult for even the most devout Apple fan to swallow, especially if they just bought a 4S a year ago. You can trade in last year's model, however, and receive up to $330 back, which is cash you can put toward your new smartphone piggy bank.

Online trade-in sites such as Gazelle, NextWorth, BuyBackWorld and BuyMyTronics offer stellar deals, and more mainstream sites such as Amazon, Best Buy, eBay and RadioShack offer trade-in programs. Apple even has its own Recycling program, where you can send them your iPhone 4S to recycle and they'll give you an Apple Gift Card for the amount your device is worth.

Before you pull the trigger, there are a few things you should know. Gazelle, NextWorth, BuyMyTronics, BuyBackWorld and eBay Instant Sale will give you cold-hard cash for your iPhone 4S, sending if to you via cash, check or PayPal (although you can also opt to get paid via gift card with some services). Trading in via Amazon, Best Buy and RadioShack will get you gift cards to the respective stores. And although most trade-in services can take about a week to pay you, if you need the money fast, BuyBackWorld issues payment within 48 business hours.

We did some sleuthing to see which services offer the best bang for your buck. (For this story, we assumed the iPhone 4S you're trading in is in good quality.)

First, although Amazon, eBay and Best Buy's trade-in programs gave us the highest estimates, the sites were also clear on noting that you can receive "up to" those amounts. That means if your phone isn't up to their standards of good quality, you won't get as much dough. We left these results out of our comparisons, as it's a rarity that you would actually receive the full value.

Second, it's important to note that AT&T models of the iPhone 4S from all trade-in sites were worth more cash than Sprint and Verizon Wireless models. Although we can't say exactly why that is, some speculations are that it's because AT&T was the first provider to offer the iPhone in its lineup, and AT&T's iPhone comes with a SIM card, so users could potentially unlock their iPhones and use them on T-Mobile.

As far as the 16GB iPhone 4S goes, Apple's Recycling Program gave the greatest value of $285. BuyBackWorld gave the next greatest, offering $282 for AT&T models and $250 for Sprint and Verizon models. NextWorth came in third for the AT&T model, offering $280 for the AT&T model and $245 for the Sprint and Verizon versions. Offering the least for the 16GB version through AT&T is RadioShack ($245), and the least for the Sprint and Verizon models is $224 through Gazelle.

If you have a 32GB model, expect to get a bit more money for your iPhone 4S, but not much. Bringing up the lead again is Apple, offering $330. NextWorth came in next, offering $285 for the AT&T version and $273 for the Sprint and Verizon versions. Next in line is BuyBackWorld, which offers $285 for an iPhone 4S through AT&T and $270 for phones with Sprint and Verizon. RadioShack gives you the least value, taking $260 for an AT&T version and only $240 for models through Sprint and Verizon.

Apple offers the most in both models through its Recycling Program, but it's worth noting that you'll receive an Apple Gift Card for your trade-in. This is great if you want to buy the iPhone 5 right off the bat, but if you just want to trade your phone in and keep the cash for something non-Apple related, you may want to go with a trade-in that gives you cash.

Although these values vary day-by-day, there seems to be a consistency in BuyBackWorld and NextWorth giving you the most money for your iPhone 4S. And RadioShack seems to consistently draw up the rear, and you can't even get cash from that trade-in program. Just think: If you use one of these trade-in services that give you the best value, you can buy an iPhone 5 with the money you received, and have some extra cash to spend on whatever you like.