Good wheels costs 500-1000 $/E for aluminium, carbon costs more, but for most people is really not neccesary. Premium tires like GP5k cost close to a 150 a pair.
Not saying that the wheelchair is provided with these because I haven't checked the spec, but saying you can have a bike for $300 is like saying you can buy shoes for $10.
Not saying that the wheelchair is provided with these because I haven't checked the spec, but saying you can have a bike for $300 is like saying you can buy shoes for $10.