For price point, the Riva 510 kit at liberty flights (LF) runs just over $30 after the october20 20% discount. This gets you two 750 mAh batteries, chargers, couple of atomizers and carts. There's a very active liberty flights group in the ECF Suppliers forum area. If you were a pack a day or so smoker, the two batteries should be fine to run a full day. (pop one on the charger when you switch to the second)
I'm a huge fan of cartomizers (cartos) instead of standalone atomizers -- the Boge 2 ohm low resistance (LR) cartos are available from liberty flights, litecigusa, many other places. Pick some up from LF at the same time as you get the Riva, use that discount. A Boge 2 ohm on a Riva battery gets you decent power, which means good warmth and vapor production.
Run time on a cartomizer varies, I do about 4 days of heavy vaping -- 22+ ml of eliquid -- before a carto needs to be either cleaned or tossed. Cleaning isn't that hard, but even if you choose to toss them that's only about $0.40/day for cartos (a 5 pack runs about $8).
Keeping cost down = do your own filling with eliquid. This is pretty simple, opens you up to a wide world of eliquids. A few good vendors, smaller, are kickbassvapor (desserts, some tobaccos), backwoods brew (tobaccos a specialty), Southern Ambrosia, Purevapes. A typical vaper runs about 3 ml a day (I'm closer to 6 ml, high end of the scale, but that's also on a high voltage PV), so a $12 30 ml bottle means about $1.20/day for liquid. There are a bunch of other eliquid places, BlueMist has some low prices, Good Prophets, FreedomsmokeUSA,... Check out the Pay-it-forward Deals and Steals thread -- people post latest sales info there. (My signature has a link to PIF).
Ultimate lowest cost on eliquid comes with picking up do it yourself (DIY). This isn't particularly hard, cuts eliquid cost down to around $4 per 30 ml, but for people who are really new I'd suggest trying the commercial vendors first, see what kind of stuff you like.
Whatever you go for, probably pick up a third, spare, battery, to cover you when you get a failure. Not necessary immediately, but it's just one of those things most of us end up doing. If you were a fairly light smoker, say at the 1/2 pack a day level, then the single Riva kit might be enough -- you might only use one battery in a day, with the second battery counting as your spare.
Note that the Rivas (and egos) are manual -- small button to push. Not a big deal if you're already used to PVs.
Good luck!
