Contrary to what other Realtors have suggested, if your house is worth at least $100k then I would contact a very experienced appraiser to give you a very educated idea of value "as is".
Depending on what "a lot" of work means, you may want to suggest to your Realtor that the house be offered as an FHA 203K Simplified Fixer Upper house. This will allow a buyer to put only 3.5% down payment and then any work that needs to be done can be finished "after" closing. As long as the total fix up costs are less than $35k and there are not structural repairs needed, it should be fine. Otherwise you will get a rock bottom, lowball, CASH offer price. Even if it needs a new roof, that's not a problem, it can go on after closing. You will get less than market value for a house in good condition but if you don't have the money or desire to fix it up then you will receive less money (net).
An appraiser will provide you with an unbiased opinion of "market value" - a realtor will provide you with a biased opinion of "selling price".
An appraiser will provide you with an "as is" value, and an "as repaired" value, and address concerns that may arise when a buyer's lender requests an appraisal for financing (Conventional or FHA) - a realtor will provide you a CMA with a suggested selling price.
An appraiser will use "justifialbe comps" with "justifiable adjustments" for characteristic differences, and other relevant market data to determine an accurate market value - a realtor will use comps and manipulated market data to suport their listing price, and ultimately their commission.
An appraiser is licensed by the State to determine "value" of real estate - a realtor is licensed by the State to "sell" real estate.
The choice is your.
Their competitive analysis will give you a better position to assess the market value of your home "AS IS" and to see who you might work with best.
They might also give you some very valuable insight as to "elbow grease' improvements that will cost little and make your home far more acceptable to a buyer. (ie CLEAN CLEAN CLEAN always sells faster in my experience)
THIS IS FREE.
Then call a bank qualified appraiser if you feel you need to. This will cost you money.
Although, an Appraiser can give you the worth of your house, they will not be able to give the market value. Call me, at McGraw Realtors, (918) 592-6000. I will be happy to come over and give you a current Home Market Analysis.