FWIW, if you would want/need to service them, I would consider $300+ to be too much for this particular set, I would be looking for something closer to $200. Consider the cost of the service kits and how easy it would be for you to find a shop that would want to service them...ScubaGaskets has service kits for TecLine regs, e.g. Service kit for TECLINE 1st Stages R2 Ice, R2 Ice, R2 Tec 5-Port
At least some of their first stages indeed have a design very similar to Apeks DS4/DST, but the HP seat is different as far as I remember. The second stages I've seen (and serviced) were unbalanced downstream regulators, unlike Apeks.