An additional note is that you can simply mine your own fuel if there is an ice belt in the system. All you need to do in that case is haul industrial trade goods in. Since each race's POS uses a different type of isotope to fuel the shield, this is only really useful if your POS is of the right race for the type of ice you are planning on mining.

Be aware that ice refines at 100% efficiency at a POS refinery if you have a good level in refining, compared to a much lower yield for refining in stations. Even the worst POS refinery will refine ice at 100% and it only needs to be online for a few hours while you are refining, so you can keep it offline when not in use to save CPU. This means that it is possible to run a small POS as an ice refinery.

SECURITY ISSUES
Security ratings for the systems you use are a bit of a non-issue. A POS can only be placed in a system that is below a true security rating of 0.4. The exception is that you can place one as far up as 0.7 if you have good enough standings with the faction that hold sovereignty in the system. These 'high sec' structures cannot run reactors or mine materials and are used for supplementing factory and laboratory services in your area, as well as for use as bases of operation in systems without stations. However, without moon mining and reacting to bring in cash, a POS in a high security system is a hard one to make profitable.

WHERE TO SELL PRODUCT
As everyone knows, the centre of trade in the Eve Isk universe is currently Jita. With POS products, from raw materials to intermediates and all the way to complex materials or even Tech II components, should you choose to build them, Jita's marketis the throbbing hub of trade. Indeed, wherever in the universe you produce your product, selling in Jita is your best bet. A close second would be Oursulaert, where a lot of the Tech II producers and component suppliers purchase their materials if the Jita market is scarce and where some producers are based. So making those few extra jumps to Oursulaert could prove profitable as well.

The ideal situation for many, however, is to get a sale contract. Many people will buy some or all of your product at the source or at the nearest 0.5 or above system to your POS network, minimising the work you have to do. Some others will pay above the market value for you to move it straight to their home base and sell it to them there. Often they are looking for a discount over market prices but a good buyer or heavy Tech II producer will offer more than market value for your products, knowing that a regular product keeps their industrial operation running consistently and smoothly.