While it is possible to find inexpensive laminate at Costco, IKEA, etc,
the accessories such as the Base Board (sometimes called Wall Base) and
3-in-1 underlayment seem to be unproportionally expensive. For example,
Harmonics laminate for my whole house would cost me less that the Base
Board and 3-in-1 underlayment for the 2nd floor alone. I assume
laminate $1.30/sqft, Base Board $2.50/ft, and 3-in-1 $0.65/sqft.

Painted Base Boards are, of course, cheaper, but they don't look good
either.

Is there a reputable online source where I could buy Base Board and
3-in-1 underlayment at reasonable price ?