i don't know why, but I am the worst sharpener in the world. I've had the small kits with 2 stones, i have the smiths little travel keychain doohicky with the carbide and ceramic sharpeners. i just suck at it. i think it's almost a natural talent you have to have, a buddy of mine in the Marines had one stone and would walk around taking everyone's knives and sharpening them razor sharp. I dont know how he did it.

i saw a youtube video of a kit where it holds the sharpeners and you lay the knife on a platform and go to town, and it sharpens razor sharp and quick too. when i looked it up it was $200+ but now i can't remember the name of it.

anyhoo, are there any cheaper comparable items that work well?

Get either a Spyderco Sharpmaker or a Lansky kit.  They both let you set an angle and make it super easy to maintain the angle over the whole blade

I like that lansky kit.

Now, I don't know all the types of blade types, but what about sharpening hollow ground and convex blades?

For convex you can use sandpaper and a mouse pad.  There are quite a few youtube videos demonstrating how to do it.  Hollow I have no idea about.  Hopefully someone else will have an answer for that