How are the gutters of the house? Are they intact and where do they exit at? Do the downspouts terminate at ground level next to the foundation or do they have extensions on them to carry the water farther away from the foundation? Proper mitigation of rain water via proper placement of gutters can very easily cure the wet crawlspace. Also was the water discovered after our recent period of 8+ days of rain?
As for the sewer lines have you checked with the local authority to see what they distance of plumbing that they cover? Do they only cover the main line at the street or do they cover the line from where the house connects to it to the main line? Find that out before you start to pay for something that might already be covered by your local taxes.
Personal recommendation, invest in quality dehumidifiers due to the fact that if you deal with more properties after this you will need them again. If you go this route, get ones that have internal pumps. Place one or two inside the house and do the same under the crawlspace. PM me if you have more specific questions on such.