They all have the same effect but the big differences in price are how efficiently they utilize the weed and how long they take to heat up. a $50 vap will use a lot of weed and take about 45 minutes to heat up before you can use it. A more expensive, say starting around $150, vap will use very little weed and heat up in 5 minutes or less. Really, when you consider how much less weed a more expensive vap uses, it's cheaper in the long run to get a good one. Depending on the cost of weed where you are you'll probably make up the difference after you've gone through a 1/2oz -1oz.