Macro lenses are designed to eliminate as much distortion as possible, in order to have a
'flat field'. This is very important for copying flat artwork, print details or stamps, for example. Not so important for 3 dimensional objects though, so extension tubes are fine. Macro lenses are also designed to be very sharp, hence their relatively high price given their focal length and maximum apertures; for eg; a Nikon 60mm f2.8 macro lens costs around £500 or more, where a 50mm f1.8 lens, despite having a larger aperture which usually means a higher price, is around £180 or so. There's a lot more going on, optically, with the macro lens though, in order to eliminate that inherent distortion. The lenses will invariably be sharper than standard lenses. So, the ideal choice, but you can get a set of extension tubes for Nikon for less than £50, so, a tad cheaper. You might not get such high magnification though; a macro lens will often give you a 1: 1 ratio, meaning something that is 1cm across, when photographed at the closest distance, will be 1cm across on a full frame sensor. This will be different on a D3200 though, as the image will be cropped, meaning the subject will appear even larger in the final image on screen. A set of extension tubes might only give you 1:2 magnification, meaning a 1cm subject will only appear 0.5cm across on the full frame sensor.
Also; when using extension tubes, your maximum effective aperture is reduced, the closer you focus. So a f2.8 becomes f5.6 by the time you're at minimum focussing distance. This doesn't matter much in terms of focussing, cos your depth of field is extremely shallow anyway, but of course matters in terms of light.
It would be a good idea to read up on the subject, either on forums or other online articles. Extension tubes are a good place to start, and you can still have loads of fun shooting with them. With your D3200, you'll lose automatic control of the aperture, and you'll have no AF, but you can still check exposure in the playback of course. Have fun!