Call local shops and find out. Itll vary by your location in the country. Provide a list of all the parts you have if you wish to get a realistic estimate from our seasoned members because we have no idea if you truly mean EVERY gasket and seal.
The more difficult to replace or time consuming, the higher the cost will be. A rear main seal and/or transaxle seal will cost a lot more than say, a distributor or camshaft seal. It's not going to be cheap (by my standards) to replace all your seals/gaskets but if you are adamant about it, consider replacing other worn components while you have the mechanic pull your engine and trans apart.
