Buyers don't pay the real estate commission (agent fee) the sellers do. Before you close there will be a home inspection at your cost (usually about $400-$600.) Then of course there may be moving van costs once you close.
There will be some additional closing costs to you which can include: prepaid property taxes, prepaid homeownwers insurance, filing fees, attorney fees, one time title insurance fees, prorated sewer/water etc. Your attorney can and will give you a more exact amount once the closing is scheduled. Even in a cash deal, it is advisable to have an attorney representing you.
With or without a mortgage, there will be property taxes and homeowners insurance due annually, and of course if you are living there, montlhy utilities (electric, water, sewer, phone etc) and the usual home maintenance issues that arise when you own a home.
Hope that helps.