I bought a cheap auction site special about 6 months ago for just over £20. They are a bit dearer now.
Very low tech and basic but, so far, I have used it to chrono a springer, pcp and 22lr rifle for separate use with strelok pro and to set up the ballistic calculator on my Arken Zulus. I haven't got another chrono to compare accuracy against but all seems to work so far. Ideally I would like something a bit more substantial but it has served the basic purpose. I then inputted my fps pellet velocity and pellet weight on a ft/lb converter website to work that out too.