Interesting question... i'd suggest you stick within your own budget for VHF and GPS, and decide what you really want to do with the kit, mounted VHF sets have the advantage of a higher fixed arial which means greater line of sight, but they cost a bit more than a hand held VHF, handhelds have the advange that you can take them with you when you leave the boat somewhere. Handheld GPS systems are great too but of course the nice wide screened fixed map plotters are a luxury to have. One good point though is make sure everything is 100% water proof, especially as your on a small boat.
Icom make some very nice waterproof VHF hand held radios and fixed radios, when you pick a GPS make sure its also completly waterproof, Garmin make a range of hand held water proof GPS systems but be carefully if you buy a mounted Garmin GPS as they need to be protected by a screen or set into a consoul as they are only deamed as splash proof not immersion proof, great on bigger boats that stay pretty dry but i'd image on a 4 metre boat your going to get wet, to my knowledge Hummingbird are the only maunfacturer to make a completely water proof gps plotter ( i may be wrong)
End of the day its all about what you want to spend and what requirements your going to put on the kit, do your reasearch and ask lots of questions, most people here have differing opinions and by asking your'll get a good idea about the product before you go and buy it.
Here' an idea for you, buy a Hummingbird Matrix 55 from this guy called Pat at:
they retail in the UK for about £550 ish he'll sell you one and ship it over via UPS for £267 ish + the duty will bring it to £300 ish and with the spare £250 you've saved buy a cheap Garmin waterproof handheld off ebay as a back up for about £100 and you still have £150 left over to buy a handheld VHF radio.