Sorry to hear you missed out on the 8"
OMG! Where to start
First and foremost - if $$ is the limiting factor go the 8"
Having said that - try the classifieds on here - even a post in the 'wanted' section might bring you a result you weren't expecting (lots of us have waaay too many scopes that we don't know what to do with). I've seen 12" dobs go for around $500
Then - what do you want to 'find' in the sky - Planets, the Messier objects, Lots of other funky deep sky stuff
These are all do-able in an 8" and may take you some years to get through - maybe long enough that you eventually decide you are addicted and NEED a 20" dob!!!
A 10" will give no 'real' difference other than letting you collect a bit more light and making objects a bit brighter. The Focal difference isn't a real issue
My 'choice' would be the 8" and then use the spare cash for other stuff
The other stuff could be...
EP's, your scope should come with at least 2 EP's - these are a great start, add a 2x barlow and suddenly you have 4 EPs - don't race out and buy a TV Nagler yet, contact someone near you (here on the forum) and ask to look down their EPs - this is a great cheap way to decide what EPs are 'worth' to you
Clothes - no, really, get some warm stuff - you'll thank me for this when your toes aren't frozen
A chair - doesn't have to be an 'observers' chair but being comfy at the scope makes the time fly by
Dinner for your significant other - they have no-idea how much tuime you are going to spend outside
That's about it for me, and remember when you do eventually decide that you need the bigger scope (and you will) you can sell the old one here to another person beginning their journey.
Hope this helps
VAZ