As a single tech doing this, you're doing fine. It depends on how indepth you want to go with policies and what the requirements are.
DNS is configured when your promo a 2k8 server to a DC. Default GPO will be in place. I'm guessing you probably manually connected the printers and didn't use print management. That's fine, that'll take some extra time.
Printer drivers will be an issue. 32 bit on a 64 is a bit of a pain. You would think printers would get easier but they have not. You'll have to work on that one to get it working.
It is a small environment with most of the basics in place. An engineer rate is generally $165-$185 an hour if you had a pre-determined amount of time in it. That is considering everything should be laid out, no time is wasted trying to figure out how to do things (get printers working for example). On top of that you should document everything, provide some form of documentation to them and include 6 months of additional support from the end-date of the migration.
It appears to me that you have started without a contract. It'll be a hard pill to swallow but the company knew that by going with an individual and not with a company that can provide a team and get it done in 1-2 standard working days.
Depending on how much help was provided, how well documented, and how well planned out it was, I would in your case target the $5,000 mark. You could range frmo $2,500 if they helped out and did a lot of work with you to $7,500 for doing all the work on your own, providing documentation, and even some additional support.
In some cases you could exceed $10k. If a company came in and did this, I would say it would take them 24 hours - three eight hour work days - to get everything together. Total cost $5,000. $7500 if you want to offer 6 months of additional 24/7 support or 1 year of 8-5 support.
With that range you can start to determine what you would consider fair. If you know them you can cut them a deal. If you don't, you may want to charge a fair amount. If you do it too cheap they may get someone else to look into it for future work.
Hopefully that baseline provides you some help.