Having reached its first birthday only last week, the iPhone 4 continues to dominate smartphone sales-charts, the news, and journalists' top phone picks. With its app store in a dominant position, a great music store in iTunes, and a very desirable design, the iPhone 4 could well be more in demand now than when it was released last year.

But it’s still prohibitively expensive for a lot of people. So we’ve called in our contacts, antagonised phone networks, and combed the net to bring you the best iPhone prices available today.

The cheapest iPhone 4: Brand-new, SIM-free

Apple’s own online store has the best retail prices on SIM-free models, starting at £510 for the 16GB model in Black or White. SIM-free means no contract- you’re not tied down to what feels like an eternity of monthly payments, and you can pick and choose the network.

This means you can go for Three with their unlimited data, or O2’s network of free wireless hotspots if you live in a built-up area.

Other stores are generally pricier; Amazon sells new 16GB iPhones from its third-party vendors starting at £438, which are covered by Amazon’s “safe buying guarantee” hopefully guarding against unscrupulous types.

iPhone and iPad combo deals

Orange has recently announced its own combination deal, giving customers a 16GB iPhone 4 and a 16GB iPad 2. On a 24-month contract, you’ll have to pay £99 upfront, and an additional £65 per month.

Take out the £510 price of the iPhone and the £499 iPad 2, and it works out to around £27 per month for 600 minutes, unlimited texts and 2GB of data shared between the devices.

Getting cheaper: Second-hand iPhones

Quality will vary hugely on these; you could get an untouched iPhone with only the protective screen sticker missing, or a scratched, dented mess of a smartphone. On Amazon UK, second-hand iPhones start at £438 for a 16GB model.

Some of these are still locked to certain phone networks, but if you’re willing to transfer your number across, you’ll find these locked iPhone often significantly cheaper, hovering around £400 on eBay UK.


Finding a refurbished iPhone 4

Refurbished phones typically come from big retailers, stocking unwanted or slightly faulty handsets that have been repaired, but remain in a used condition.

Searching the web, we found fossilised forum posts pointing to now non-existent pages. Apple now doesn’t seem to stock any refurbished models of its current iPhone range, though it certainly used to.

We’ve been in contact with several major phone networks. Vodafone told us that they’ve never stocked refurbished models of the iPhone 4, whilst O2, who were rumoured to have offered cut-price contracts on the older iPhone 3GS, said that they do offer reconditioned iPhones "on a very limited basis". Any refurbished models would be shown on O2's online store.

Here's the 16GB iPhone 4, refurbished, starting at £21.50 per month with an initial payment of £249.99. That's more than a £50 saving compared to the brand-new model on O2, and we think offers the best balance between saving money, getting your iPhone in good condition, and avoiding disappointments/scams.

UPDATE: Orange has passed on information that they also (rarely) get returned iPhone 4 devices, which are refurbished and offered on its reconditioned phone site. Any available will be publicised there, but the spokesperson reiterated that they were very rare. Keep refreshing that page!

 

Conclusion

The sad truth is that whilst demand stays high, so will the iPhone 4’s price. If you’re willing to make a relatively long-term commitment, you may be interested in Orange’s iPhone and iPad combo package. Two years is a long time; especially when the iPhone 5 is roughly pegged for a Q3 release date this year.

A bit of flexibility in regard to second-hand, refurbished and network-restriction will see the average price tumble- especially if you search carefully online. Remember; if it’s too good to be true, it most probably is.

Another option we’d recommend is going for the older, and significantly cheaper, iPhone 3GS.

It may not have the retina screen of its younger sibling and lack a front-facing camera, but you’ll still have access to the majority of apps from Apple, iTunes and the smooth reliable iOS system. It’s worth noting that the iPhone 3GS will also be getting the iOS 5 upgrade later in 2011.