The Maxon headsets like you use are discontinued and I do not know of any similar equipment still on the market. Manufacturers seem to be moving away from 49MHz to UHF FRS for 2way applications and leaving 49MHz to the "baby monitor" type stuff.
In your price range, the best bet is probably a FRS radio with an accessory headset. The Motorola TalkAbout radios offer a variety of compatible handsfree headsets and the total cost of the radio and headset is under $ 50. It would not be compatible with your existing 49 MHz equipment but FRS units are now available from several manufacturers and may be the best way to go for future availability.
Here is a link to 2 types of headsets and a list of compatible FRS radios: