First of all - welcome to BC !
Your best bet is probably to try fixing it yourself. The problem with water is not that it causes corrosion, unless the spill was a relatively long time ago, but, especially if you live in a hard water area, the salts and minerals in the water cause it to conduct electricity which obviously causes problems.
As a first step go to YouTube and enter the make and model of the laptop + 'teardown'. You are almost certain to find at least one video on how to do it, or try the iFixit site. If after having watched a couple of videos you will be in a better position to decide if the job lies within your skill range. If it is then go ahead - take it to pieces. If you find any dampness anywhere inside it then it put it in a warm dry place - an airing cupboard ? - for a couple of days then clean all the connectors, gently, with cotton buds and iso-propyl alchohol. If you find any 'crud' on the motherboard or the RAM chips you can clean this off the same way. Then put it back together and see if it works. And if you have to dismantle any heat sinks as part of the teardown then you will need heat sink compound before you re-assemble. Clean the mating surfaces thoroughly with the buds and alchohol and apply a small amount of compound to one of the clean faces.
Parts for Apple computers tend to be expensive, your best bet is to find a seller on ebay with a good reputation for any you might need.
If all of this is out of your comfort zone and the laptop is definitely not working, your best chance is to look for a second hand one.