What is the cheapest but best BMW 3 series; and how much mileage do they last; looking to spend arou

I am looking to buy a 3 series i dont know anything about BMW are they reliable; how many miles are they going to last me; i am looking to spend 15k to 18k; i know its a buyers market; can someone give me and ideas on what I should be looking for; is 50k in mileage if its a 2003 too much; i need alot of information so I can figure this out but I dont know much about BMW and how reliable they are and i need some information; can anyone help; i want to get a decent 3 series but the thing is i am going to have to trade in my mercedes that is worth like 25k; i cant sell it because of the market; i have tried for like 6 months its a 2003 mercedes benz clk 320k black with 40k miles in mint condition but in oklahoma noone needs it; could anyone give me advice on what they they i should do trading it in and making sure i don't get f'd over like the car dealers can do; i am not going to tell them i have a trade in ; i just want to make sure i get this to work any input would be appreciated

What is the cheapest but best BMW 3 series; and how much mileage do they last; looking to spend around 17k?matchless

I own a 1997 BMW 318i, I purchased it new and I love BMW. It really is the ultimate driving machine, and I bought almost the cheapest one at the time. I had three problems with it all fixed under the warranty. Catalytic converter when out , the ignition switch broke and the brake lights switch also broke. They all happened in the first two years I had the car. After that, I have had no more problems with it. I still have it and love it. It still drives the same as the first day I took it out of the dealer, now it has 130K miles on it. Right now I drive a company car with everything pay for so I don't need to buy a car, but I am keeping my BMW, and I am definitely buying another BMW next time I decide to buy another new car.