If you are dealing with a product which carries a high risk of being charged back, then it would be a good idea that you obtain a high risk merchant account from a payment gateway which will be able to cope with a large demand.
High risk merchant accounts can also help you to avoid selling products to fraudulent buyers. The following is a list of high risk products/businesses, if you sell or provide one of these products or services then you should have a high risk merchant account.
# High risk categorized product/services:

Gambling
Casino
Jewelry sales
Online auctions
Online dating
Online Hype site
Political organizations
Weight loss products
Pharmaceuticals (enhancement)
Adult Product
Alcohol
Travel
Astrology/Psychic
Computer Hardware
Computer Software (electronic download)
Computer Software (tangible)
Tobacco
Dating Services
Debt consolidation/management
Discount clubs
Discount health cards
Discount/Prepaid phone cards
Financial Advisory Services
ISP/email services
Membership organizations
Miscellaneous food sales
Mobile services

# High risk business- payment service providers:

Charge.com
Instabill
gspay
worldpay
ChronoPay
netbill
ccbill
ibill
metacharge

-Bob