From the impact doc:
http://www.fda.gov/downloads/AboutFDA/ReportsManualsForms/Reports/EconomicAnalyses/UCM394933.pdf
Pg. 25
"This proposed rule would also extend the FD&C Act tobacco authorities to tobacco products that do not fit into traditional product categories, such as electronic cigarettes or nicotine gels. Current estimates in the press indicate that sales of electronic cigarettes are expected to be between $1.0 billion and $1.7 billion in 2013. Cigar sales are forecast to be about $8.1 billion in 2013 (Ref. 49, [Euromonitor, 2012]). Therefore, forecasted sales for electronic cigarettes are 12 to 21 percent of forecasted cigar sales. Using 15 percent as our best estimate of the size of the electronic cigarette market relative to the cigar market, and assuming the number of products and UPCs is proportional to dollar sales
, we estimate there currently are 1,675 e-cigarette formulations and 1,717 electronic cigarette UPCs.
22"
22A single online retailer, myvaporstore.com, claims to sell over 1,000 unique products <http://www.myvaporstore.com/aboutus.asp>. FDA analysts counted over 150 unique products among just the top 5 brands.