There are inspectors available but it's best to select a house that you are interested in first and have a passing inspection be a contingency on the purchase contract. Note most properties are sold as is so don't expect a seller to fix anything but it is very typical for most purchase contracts to allow 10-15 days for you to get an inspection completed for your own personal peace of mind before getting to far into the transaction. Price varies depending on square footage of the property.
First you need to make sure the person has a clear title for the property, a title search is needed and verification of the identity of the owner.
I agree with Larry.
Until you have a formal inspection, you have no idea what mess you are getting into or how bad is going to be the bill to repair the issues.
I would make the Purchase agreement contingent on the following:
a) Closing must occur within 90 days of the signing of the Offer / Purchase agreement, otherwise you are to get your deposit back. This would have an out where both the seller and buyer may agreed to a time extension. Use a number of days you are comfortable with but in most cases 90 days is good.
b) Clear title Lawyer
c) All taxes payed and up to date
d) Home inspection show no significant issues that would cost the buyer more than X amount to repair. Period for this to start after clear title has been verified.
e) Home appraisal is equal or more than the price agreed to in the purchase agreement. You don't want to overpay for the property. Period for this to start after clear title has been verified.
Once you know the condition of the place and have an idea how much effort and money it will take to get the place in shape, you may want to either walk away and get your money back, or renegotiate a new offer.
Given the glut of properties, few sellers would not agree to the above, make sure it is part of the offer agreement and in writing, or you may loose your money. Always have the Owner sign the agreement first, then you sign it and give it to your lawyer.