Speaking from the point of view of an Aussie who has had to look hard at this issue because I needed to save a buck yet still end up with quality gear, it should be noted that the cost of shipping alone for slats to come from the USA should just about cover the cost of .010" shim stock (or spring steel if you prefer to call it that) over the counter, right here in AU. As I mentioned above, there is no down side to blued steel over stainless accept by the perception that stainless must some how be better than spring steel simply because it is stainless.
Also, buying a heat blanket direct from MEI, who actually make heaters for most other suppliers in the USA, will be shipped to AU for around the same price that other vendors in the USA will sell the blanket only for, and then you will still need to pay 30 to 40 bucks shipping on top. The other upside to ordering a blanket direct from MEI is that you can chose the options that best suit YOUR needs.
For example you can choose to have an exit tab for the wiring either to the left, right, centre or even middle of the blanket thus protecting the wires from being fouled in YOUR design of bender. Most other suppliers order your blanket with the wires just short stopped at the centre butt of the blanket with no exit tab at all because it cost THEM less this way. Also if you want, for just a few bucks over a standard blanket, you can order an in built thermocouple for digital temperature control of the blanket just in case you decide to get a PID down the track. You can even specify a "J" type or "K" type or what ever type thermocouple turns your PID on...or off. You can select blanket dimensions, wattage PSI, voltage etc, etc, etc and with all the bells and whistles added you will most likely still pay less than anywhere else in the USA.
Just my 2c
Cheers
Kim