SLP Sound Production

I am looking to upgrade my equipment and stepping up my game and so I'm looking to add monitoring systems for clients, directors, producers, etc. I've been hearing "Comteks" everywhere I go so I decided to give it a go and found what I thought it was a great deal on Ebay, and got a set of old Comteks but they aren't anywhere near the quality and expectations I had in mind. Would it be only a matter of upgrading to the newest of their systems or are there any other systems I should be looking into? I considered buying more 2.4GHz systems that I use for my Lav Mics which are cheap, but the range is not great and specially when you are indoors and there is some mass (walls, columns, etc) in between the TX and RX. What do you guys recommend and what do you guys use to provide monitoring? Is there a way to get something cheap and functional or you gotta take the hit and invest whatever's needed?

I'm upgrading my gear and stepping up my game and need to get a monitoring system, for either clients, directors, producers, etc. I've hear a lot of talk about "Comteks" and so I went on Ebay and bought an old set which seemed cheap and like a great deal, but after it arrived and I tested it, it wasn't anywhere near to the quality and expectations I had in mind. Is it cause they are old, and the new models are the way to go? or I don't really know, I've tried to do some research on this, but I'm a bit confused. What do you guys recommend and what do you use to provide monitoring to multiple people?