You can now easily search for these kinds of patterns on NameBio and determine values by looking at real sales. Here's some info:
ABA format, only one publicly recorded sale in 2015 was 989.com for $818,181. We have 12 sales of this format in the database:
http://namebio.com/?s=gMzcTM4MzM
ABBA format, only one publicly recorded sale in 2015 was 4994.com for $16,100. We have 9 sales of this format in the database:
http://namebio.com/?s=QNycTM4MzM
ABNBA format such as 06360.com saw many more sales, mostly high three to low four figures if containing a zero or four, mid four figures without "bad" numbers:
http://namebio.com/?s=QO0cTM4MzM
ABBBA format and ABABA formats haven't had a publicly recorded sale in a very long time, no point in even publishing links to them.
ABAABA format such as 434434.com had only two publicly recorded sales last year, the one mentioned for $713 and another without "bad" numbers" for $1,319.
http://namebio.com/?s=AO5cTM4MzM
Other 6N palindromes didn't have any recent sales. Hope that helps.