30 watts is not enough if you want to build on RDA's. Sure it will fire the Kayfuns and other stuff
Lighning Vapes has one of the best chargers on the market the efest luc v2 and v4 use discount code LV20 It is also a great place for Kanthal. Plus they have free shipping. And they carry the Samsung 25r batteries. They also list Sony's but I have never bought one from them so cannot confirm authenticity. But I did purchase a Samsung from there.
Efest LUC V4 LCD & USB Charger | Lightning Vapes
Honestly SIgelei 100 watt is a great purchase. look around I have seen them as low as 79. You can also get them from eciggity.com for about 100 and then use reddit10 discount code. Free shipping from them and it is pretty quick for me on the west coast.
With a Sigelei you are looking at about 175-200
charger $17
Batteries $25 for 2 sets
Mod $90
Kanthal and rayon or cotton = $20
RDA or Lemo = $35
total = $187
You can save a little money buying one set of batteries to start so minus 12 and cheaping on the cotton and kanthal you can easily get that to about $10. And if you are really on a budget you can pick from the various clone RDA's for about 20 on eciggity with the discount code it would run about 16ish
so cheap route = -35 for a total of 152 or close
Edit - eciggity has the 100w no screw holes for 89 so minus 10% knocks another $9 off of that. But I would pay the extra 10 for the floating pin.