I’d like to get an HPS system but I don’t know which brands are reputable?
My concern is that HPS can cause heat.Are they safe if set up correctly?
Most HID HPS mainstream brands are reputable and pretty similar. LEDs are a little more difficult to find a good one without being overcharged, but again if you stick with more mainstream brands you’ll probably do fine. In general, however, most mainstream LED brands are significantly overpriced.
I personally prefer LEDs, but I also know how to build and repair my own, so start-up cost is not a consideration when comparing overall costs for me. Latewood knows of a very affordable HID system that he recommends, that you can find on e-bay for a very reasonable price.
Here is a chart that shows long-term and short-term costs comparisons with some major brands:
HIDs, whether MH or HPS, do create a lot of heat and you will need to be able to regulate temperatures in your grow area. It depends on a lot of factors how much heat will be created (mostly overall watts) and how much you will need to deal with (open light fixture or enclosed inline duct system). There are numerous ways to deal with the heat that vary considerably in price. The leaves at the canopy can withstand high temps and so say 90f/32c is not a big deal with a large healthy plant, but 90f/32c at your root zone will cause problems. Good organic soils can handle higher temps than hydro, but still can not get too high. Most people try and keep their grow room/area below 80f/ 27c. And some people like to run high temps at the canopy, especially if supplementing co2, but then that could bring a lot of other costs as you would certainly need an inline vented sealed light system to remove the heat with a HID system and kinda air tight the grow area so your co2 doesn’t just drift away.
I have bought ans used the Ipower digital switchable lamps for the past ocuple years. I bought the whole system really cheap. Generally; I do not recommend the cheapest brand, but if it works…Well 
check out Ipower @hpslighting.com I think that is the company that sold me mine on ebay.