Hey Jason,
We have clients that pay between $750 up to thousands per year for tax prep. It depends on the number of properties, entities, and states we have to file in.
For accounting services we've seen the industry norm to start around $250 per month. I believe even if you go through Quickbooks bookkeeping they now start at $300 per month. Again this depends on if you're working with someone in the states or if they are having someone overseas do the work.
There are so many factors that come into play with pricing. I hate the "it depends" answers but it really does here. For example, we once charged a flat $300/month to do bookkeeping for up to 5 properties and roughly 5 different accounts. However, we found we couldn't keep doing that because some people would have 300 transactions per month (how on a rental?) while others would have 10. Now proper accounting is still important because bookkeeping is the first and best tax strategy for most people but there was a huge time difference in the services performed.