AquaVapor sells a disposable 109mm e-cig (1 non-rechargeable battery, 1 atomizer, 2 menthol cartridges) for $8 - the "SOLO" aka "Kim One" by Kimree Technology. myFreedomSmokes sells the same model (calling it the "Freedom 1") for $10, saying "No cartridges to change." eSmokerOnline sells that model (
tobacco flavor only and without nicotine) for $9.
VaporCountry sells a disposable M401 clone (1 non-rechargeable battery, 1 atomizer, and 4 "high" strength
tobacco flavored cartridges) for $8.
LiteCigUSA.net sells the Boge Q-510 (they call it the 510-B) for $10 - a Joye 510 knockoff with 1 automatic
rechargeable battery (and charger), 1 atomizer, and 3 cartridges (18mg nicotine, menthol or
tobacco flavor). eSmokerOnline also sells it for the same price (24mg nicotine, tobacco flavor only). MadVapes lists a menthol version of the Q-510 for the same price, but they are out of stock.
The first two models mentioned might be good for a bar to carry (for their customers to use for an evening). For an individual, I would recommend the Q-510. It is called "disposable," but the battery is rechargeable several times and the atomizer is just fine (and can be used with a regular Joye 510 battery). The cartridges can be refilled with menthol e-liquid (at whatever nicotine level you want). I and many other ECF members have used it successfully (and repeatedly). It is not as good as a full-fledged Joye 510, but it doesn't claim to be ... and, at that price, it seems an excellent choice for your stated purpose.
FYI: The Joye 510 is not the only good e-cig model, but it is the most popular among forum members.