I'm going to wish you luck, BUT I've read threads nearly identical to this.
And I started the same way in 2005, I didn't buy 1 cheap $99 Avalon, I bought 3. And I bought a used Huffy with the same thin frame as the one in your picture.
Then I made 2 more mistakes, a used Western Flyer single speed and a new Sun Cruiser single speed.
So it took me $600-700 to figure out what's what in the bike department.
Likewise, I had built 10 bikes before I discovered the weakness of 16 gauge spokes, and I quickly contacted my earliest customers, said "we have to switch those out, you do NOT want to go through what I went through 20 miles from the house".
That's why I have a quarter mile of rear rims on the fence.
Same thing with $10 tubes on the rear, it comes from the experience of cutting a quarter sized hole on a shoulder, on my way to Florida, hours from a bike shop, and fixing 4 flats in one day. After the bike shop visit, no more flats.
Of all those early cheap bikes, one Avalon is still in my stable, and I used it Tuesday to make a 80-100 mile break in ride on a 4 cycle engine, (because it was the only bike sitting around halfway ready).
It did not take very long to figure out why I despised that bike. Why I wouldn't sell it to anybody.
The grips are irritating, the brakes s**k, and the front sprocket is small, I could hardly ever help the engine on steep hills, even with 7 speeds.
I know people try to do this as cheaply as possible, but realistically, it takes more than $125 (engine) and $77 (new bike) to get into this game.
My low-end estimate is $450-500 for a reliable ride.
Maybe you can get the kit around that price, but on the bike, you have to swap that rear wheel ($35-50 for 12 gauge), $16-20 for new tubes, and the saddle on the bike you link to is like riding on a brick.
Of those low end Target type bikes, the Jaguar has a better frame, imho.
Thin aluminum is not an asset at 30 mph, vibrating and riding on bumpy shoulders.
Cro-Alloy and steel hold up to the stress.
Sometimes you can find a bike worth $300-400 on Craigslist for less than $100.
