Getting level 10 tech requires a second playthrough, I'm 100% sure of it. Doing all sidequests in a single playthrough will get you to level 8 or 9, I think.
These people are all wrong!
Around the time you start getting 4th tier stuff, you should have plenty of equipment, and you'll want to start selling or gelling your less good stuff. This is a lot easier if you decide to go through the game with the same 2 people, because then you won't have to worry about equipping the whole party (except for maybe the Virmire mission, which can throw you off depending upon your chosen people) The main reason for this is that you're never really aware of the size of your inventory, and it's best to slim it down as much as possible when possible. Keep 2 at the most of every upgrade unless they have sentimental value. As you start gaining levels and the quality of found equipment follows suit, keep selling your lesser items.
But note that the higher-tier ordinance upgrades, while powerful, come with drawbacks. Snowblind rounds decrease rate of fire, inferno rounds decrease accuracy, hammerhead rounds increase heat, etc. Lower-tier upgrades don't have this problem. In particular, look out for the cryo rounds. I think they become snowblind rounds around tier 7 or 8, but hang onto them when you start getting snowblind rounds, because their shield bypass is powerful and useful later game, and the decrease in accuracy applies to whoever you're shooting instead of you.