Need help analyzing a mobile home park deal - South Oregon Coast

[Tony Ngo]

We're looking to buy our first mobile home park and need help.  All homes are owned by tenants.  Homes are older but we don't know the age of the homes It is on septic and wells.  The seller is asking $850k.  What is a reasonable number to offer?  We're looking for double digit cash on  cash return.  What's a normal cap rate for MHP? 

Here are the actual 2015 numbers from the listing agent:

23 lots: 100% rented $7535 total per month. $90,420/year

7 lots additional can be developed: need to put $15k into it to make them rent-able.  There's a wait list of 8 people waiting to rent.  

Operating expenses for 2015: $23,592  

Management: 705/month

Recycle and disposal: 490/month

Electric: 188/month

Property tax: 200/month

Insurance 55/month

Monthly water testing: 35/month

5% maintenance and repair: 293/month

What other expenses should I account for?  Let me know if you need addition info to help me analyze this deal.