=========================Well, I can tell you that the M5 can't be made much cheaper! I have to make a profit, otherwise there would be no point in producing them. I'd like to see you make one as you describe; believe me others have tried. If I could make it for $100 I would, believe me. The main pulley is manufactured on a $400k machine, it wouldn't be possible on a hobby lathe as the tolerances to accept the sprag etc. are critical. The M5 is a far more sophisticated unit than the GPL design and also lighter and far more compact. The lack of a recoil start facility has never been a problem, and on the one or two occasions someone has had a flat battery, they have actually been able to hand swing the prop (!).
You could do something IF you had the skills, but many people don't and so they have to buy. There are a few hundred of these units (the original M4 and now the M5) all over the world, with happy owners who thought the price was worth it.
Nobody is saying you shouldn't make a Profit. There is profit and then there is being Greedy! Use to be a part that cost $1 to make was wholesale for $2 and then retailed for $3. Today that $1 Part wholesales for $10, and then retails for $20. You can buy a FAG Crank Bearing Retail for $8.50, Rotax wants $85 for the same Bearing. You can buy a 2 Stroke Rod Retail for $18.50, Hotrods wants $125. A Billet 2 Stroke Bicycle Head is $80, Rotaxs 277 Head $389.
You don't need a 400K machine to make any of these parts. Christ man you can buy good used CNC machines for $1,500 to $5000. I have seen a nice 5 Axis CNC Mill go for $8000. A 5 Axis 5' x 20' Gantry CNC Router go for $7000. I recently traded a Snowmobile I had $950 in that I used for 10 years and a Homemade Trailer I had $400 in that I also used for the last 10 years, so $1,350 total, that I traded them both for a 9" x 20" CNC Lathe. 0.001" was Industry Standard for over a 100 Years and still good for 99% of the parts made, now they want to push this ISO9000 0.00005" Bull **** to cut out the little guys and foreigners! IF you look real hard you can source most Parts Off the Shelf today, like Starters, Nuts & Bolts & Washers, Springs, even some Pulleys. You can even Buy Pulley Raw Stock that already has the COG Style or Micro V already Machined. This Steel Pulley off eBay for $12.95. Another for $8.50. So why would I waste my Time making one if I didn't have to! Large Pulley for $40 NOS off ebay. I also got a 12" x 37" Lathe, I wouldn't really call it a Hobby Lathe even though that is what I use it for.