I work in a vape shop so another suggestion is to find some cheap clones on ebay and have a local shop build them but as everyone else mentioned unless you win a bid through ebay at a low price, just the mod, atty and at least one battery will set you back about what your spending limit is. then you need a charger and have to get good batteries if you plan on sub ohming at all. so in short stick with a regulated mod with an enclosed battery and a tank for now. When getting into mods you do not wanna be cheap about the charger, the batteries or the ohm reader at all!!! This is not just friendly advice this is a must if you plan on doing anything sub ohm related!!!
I go cheap on mods and attys all the time just to see what I can resell my clone setups off at in shop but all the stuff I like and keep is authentic and will stay that way because you get what you pay for. When you get into clones you are getting into bad machining (bad threads, uneven milling, etc.) and voltage drops that are unsatisfactory if you want a good long lasting mod. Mods are a hobby and very time consuming and expensive and even going cheap on mods and attys doesnt save you from having to spend good money on good batteries, good chargers and good testing equipment, just IMO