Howdy,
30 bucks is pretty slim on budget, but do-able. Did you hit up the classified section yet and check local B&M shops. Sometimes you can grab some serious deals there for what your looking for. If 30 is your total then I'd say do that if not then mechanical mods come in at that price range but you've still got the cost of charger and batteries to add on to it (and Mechanical mods are not regulated, so if you wanted that add in a kick option as well).
If you can see your way free of a few more bucks, or save up and do it once then I'd look to a descent quality VW/VV mod of your choice, just make sure that it can drop down to your lowest oHm rating that you'll go to. I don't even plan on pushing my builds below .5 but my mod goes to .15 just in case. Hardware rarely goes bad but batteries do eventually so whatever you decide to invest in make sure that you can replace the batteries as it will save you in the long run (and save the planet as well).
Some tips and tricks I've learned over the years of vaping, hopefully they help you out some in the long run.