not sure but you could make your own from some very thin carbon rod, should be able to get it from model shop.. then just use some small cable ties to put it in 'X' shape under skids ... you wont need them that long a length as heli is so small... but enough to stop tipping (maybe sticking out 5-10cm from each corner of skid.
the balls they put on training gears just help the heli 'skoot' about on floor, which can be handy for learning the controls but not esential... best to try heli to begin with on a wooden or 'shiny' floor so you can see control effects even when heli still on ground.
I would some how screw that up

Found a decent one here for the buzzflyer, but as 4#3b is pretty much the same it should fit fine
http://www.buzzflyer.co.uk/Buzz-Fly-Spares/Training-Kit/p-119-909/