A quarter wave antenna on 2 meters will be about 19 inches. You can pick up Larsen, Antennex, Comtelco, etc. 1/4 wave antennas for less than $20. They are durable, fairly wide band and cheap. You can have chrome or black, so they can blend in pretty well. That would be about as small as you want to go if you want good performance. The low profile VHF "Soup Can" antennas are poor performers and very narrow bandwidth, so they are not a good option when you will be working over several MHz of the band. They will work fine for short range stuff, but the general consensus from those that have tried them is negative. The basic 1/4 wave is about as simple as you can get, and they work quite well on the roof of a vehicle.
As for the scanner, I think you will find that most will suggest the VHF/UHF/800 Larsen receiver antenna as a good low profile option. I think black is your only choice there. I don't own one, but most of what I have read about them has been positive.
You really can't go wrong with good basic antennas. NMO mounts will give you the ultimate in flexibility, and if installed correctly, will last you a long time. Commercial grade stuff will serve you well, and I personally think it looks much better than some of the ham grade stuff out there.
Good luck!