Our barcode label formats are built using ZPL, a programming language specific to Zebra printers. We also work with Monarch (MPL) and Eltron (EPL, a Zebra subsidiary) and could adapt the formats to other languages.
We recommend Zebra as having relatively low cost, robust industrial quality printers suited to a steel manufacturing environment. We have customers who have used them satisfactorily for years for fairly high volume barcode printing.
We suggest the Zebra 105SL as a reasonably priced printer capable of maintaining a decent throughput without burning out the thermal printhead. It will print using a plastic ribbon for UV resistance onto coated weather resistant labels, so that inventory stored outdoors will not have tags affected by sunlight or severe conditions. The Zebra TLP-2844Z printer will do the same job and cost less, but because the media (ribbons and labels) are in smaller batch sizes and more expensive, and its duty cycle is shorter, you are likely to find the 105SL a much better choice.
Find out about printers from Zebra themselves or any number of online internet stores handling Zebra equipment and supplies.
Used printers are commonly available on eBay but they can be heavy beasts, so watch out for the shipping costs, and don't forget about duties and brokerage fees if you are buying internationally.
For media, the Transmatte 2000 4" x 6" is a good, coated label suited to our formats, and you will need a 4.33" wide ribbon (with 1" core for the 105SL) to go with them. Labels and ribbons are sold by the case - large, heavy and expensive for labels, just expensive for the ribbons.