I'm assuming TNG sales are much higher than ENT--
Yeah, it's not even close:
Today's Amazon UK's Film and TV (DVD & BD) rankings are:
TNG S4 #116
ENT S2 #3,222
To be fair, today is the release day of TNG S4 and ENT S2 isn't out yet. So let's compare the other TNG releases with ENT S1 and we get this.
TNG S3 #3,173
ENT s1 #24,584
TNG S2 #6,025
TNG S1 #5,582
Again, no sales numbers but these rankings show that even the 5 year old release of TOS season 1 (# 20,191) is currently outselling ENT S1.
That post from Scotty, BTW, comes from this thread
, the top of page 30.