Sure...These are modded modules...They were taken as stock to begin with and entirely reworked to become something that is much better....The prices are very fair for sure...Especially the S1S0...That one is cheap...
Depending on where you are there are modders that can give you whatever you desire both in the EU and US...These modules are from the EU and Salvation Mods has a very reputable name...You will hear nothing but praise on the forum...These particular mods are all known as great in their own way....The S1S0 is a 5150-based mod, the Mamba is based off a Framus Cobra, Kraken is based off a Krankenstein, and the Dreadplate is a recto-based mod with some extras...go to salvationmods.com to get the skinny right from the source...
Hope that helps more...If you were to purchase these mods new...You would likely pay as much or more...