The Dynacraft is crap, crap, Kuh-rap! The thing will most likely lead to frustration. The weakest and most expensive part of any used bike is the rims. Those look to be cheap awful steel rims. It's not worth fixing.
There is a certain amount you are going to have to spend to get a decent bike. A lot depends on your area. I live in Southern California. Bikes are in big demand here. A decent used road bike starts at about $160-$200. If it needs tires, prepare to spend at least $40.00. These are starting prices, not average prices.
I bought a Peugeot PH19 12 speed for $15.00 Sunday. Hasn't been ridden but a few blocks in the last 30 years. Here's what it's going to need at minimum:
New tires: $22-$60
New tubes: $6-$12
Cables: $5-$20
Grips: $6-$15
Would like to get a new set of bars. If I can find them used, it's $10-$20. The bike was a fluke. Most bikes like the Pug go for $75-$100.
There's a swap meet close by with cheap parts. That's the low end. Upper end is for bargain parts at the bike shop. or online. I had to strip it down to bare frame and use a few special tools- chainbreaker, bottom bracket lockring wrench, and a crankpuller. It should sell for $180-$200. For what the buyer is getting it's a solid deal. The Peugeot is a mixte frame model, not as desirable as a diamond frame. My personal bike was bought for $40, but ended up costing around $300 because I intend on keeping it for years. I can buy a new bike for $300.00.
Go on Craigslist everyday at least twice a day. You will get a feel for the market. I see complete bikes at our swap meet for more than the average C-list price. One guy tried to sell me a trashed-but-cosmetically-good Italvega. He asked $500, it was worth about $50.00. Tires would have cost $200! My neighbor bought a full suspension mountain bike that I had walked away from. Seller quoted me $400. It was only good for parts. Neighbor brought it by for a look over. Needed a new bottom bracket, crankset, tires, cables, chain, front sprockets, and so on. Knowledge is power.