I would do it the hard way and learn how to sharpen without any device. Once you learn how to hold the right angle, and just one angle, you will be able to sharpen just about anything, even with improvised equipment (sandpaper, metal or stone surface, edge of a car window etc.).
What I found most demanding in the beginning was to keep on grinding the bevel (??) long enough to produce a burr (which forms on the opposite side), and to do so without cheating = changing the angle to make the process faster. To make things easier I would first buy a really good coarse whetstone (I use grit 220 "suntiger", which I love) to speed up the first phase. If you use too fine a stone you will probably get bored and cheat - which usually means that the bevel will get "round" and thus, not that sharp, at all.
A set of good quality japanese stones (king, for example) does not cost that much and will last years.