Ok right, we are THE most messy, unorganised household imaginable, seriously, people just do not come round, well not more than once 
Anyway I sorted this last year. Bear in mind I have 3 boys - 10, 6 and nearly 1.
We had loads of those big flexi tubs with toys in them, all mixed up.
I think it took about a week in all.
Went through all the boxes, sorting them into sets (knex, magnetix, gears, puzzle pieces etc). I had loads of carrier bags around me.
Then we went and got a load of Wham boxes and Really Useful boxes from Staples. With lids (this is critical)
Everything has got its own box now, they get swapped around when quantities increase and so on, but basically, everything is in a clear or translucent box with a lid and they stack, so all the ones of one size can go on top of each other, and you can get various sizes so it's brilliant.
Far cheaper than trofast I think - could be wrong, but we're nowhere near an Ikea anyway.
Finally we know what toys we have got. Oh and shelf wise we got some metal garage shelves from Argos when they were reduced, which have got MDF shelves, and the boxes can go on those when you feel like having a clear floor. But I prefer just to keep them stacked.