I've looked at some 8" Dobsonians but going from the 6 to the 8, the price pretty much doubles (from ~$600 to ~$1300), this is from FLO. From Bintel, OpticsCentral, and OzScopes this goes to around $800-$900.
I was planning to spend around $600, but I am willing to go to the 8", however as a teenager I do not have a good source of income and will have to wait a couple more months.
Currently I am using a 10x50 pair of handheld binoculars that are like 20yrs old and broken, so really anything is an improvement. If the difference is that significant between the 6" and 8" I might wait a couple months and go for the 8" instead.