(1) Background: Characteristics and usage patterns of vapers (e-cigarette users) have mainly been studied in web-based convenience samples or in visitors of brick-and-mortar vape shops. We extended this by targeting customers of one particular online vape shop in the Netherlands; (2) Methods: Customers were questioned on their smoking history, current smoking and vaping status, reasons for vaping, perceived harmfulness, and potential health changes due to vaping; (3) Results: Almost everyone (99%, 95% CI 0.96, 1.00) smoked before they started vaping. A great majority agreed that unlike with other smoking-cessation aids, they could quit smoking (81%, 95% CI 0.79, 0.90) due to vaping. Almost all customers were regular vapers (93.6%, 95% CI 0.89, 0.96) who used state-of-the-art open system devices without modifications and e-liquid with 10 mg/mL nicotine on average. Vapers reported using e-cigs to quit smoking, because e-cigs are healthier, and for financial reasons. The majority (52.6%, 95% CI 0.46, 0.60) perceived vaping as not that harmful to not harmful at all, but one fifth (21.8%, 95% CI 0.16, 0.28) believed vaping to be harmful. More than half (57.8%, 95% CI 0.50, 0.65) reported gaining more pleasure from vaping than from smoking. A substantial majority (84.2%, 95% CI 0.78, 0.89) agreed that their health had improved since they started vaping; (4) Conclusions: Findings are similar to those obtained in other vape shop studies, but also to the results of convenience samples of less-well-defined populations.