Dear Chubby,
Read all of the posts on this site. Lots of info on how to get online supplies no Rx needed. They don't ask, you don't tell. Further, there is collective experience of a lot of people. they'll tell you the good and bad, how they did it.
While many people do strange things and get away with it, there are many stories here of people who messed with the urethra and bladder and did NOT get away without complications. Infections are common with medical use by doctors and nurses. So amateurs are also at risk. Stories of blood, bleeding, ER visits abound on this site with urethral play. You've been warned.
I used catheters for years, sometimes keeping them in more than a week at a time. (I lost interest four years ago) So I have experience. My advice is don't skimp and short cut. Firstly Use only new supplies. An insertion kit is under $2 and a foley catheter is $1.14 at Allegro. Why would you not skip a latte at Starbucks and buy new medical sterile stuff to put in most delicate part of your body? What is really expensive is urgent care visit for urinary tract infection. Do not experiment with amateur disinfection; you don't know if it works and you can't keep it sterile.
Secondly. Go to the You Tube school of nursing. Take classes in catheter insertion. Incidentally, learn the technique of how to put on sterile gloves. There is a procedure. Gloves are half turned down. Pick up INSIDE of right glove with left hand. Insert right hand, and pull up cuff edge with left hand. Now stick right hand under OUT SIDE of the left glove; insert hand, pull up cuff only touching outside of left glove. Now you're good to go.
Thirdly: Urine has to go somewhere. Large 2 L bags are good in bed. However to walk around I only use Conveen Security leg bags, over 10 years. The drain flip system never leaks (twist ones always leak sometime) and the leg straps are velcro closing; top one is wide, comfy. I've tried them all.