I have grown these before, and also been in places where they live, naturally, in the wild (Onslow County, North Carolina, in case you want to look up climate information for growing outdoors).
Yes, buy a young plant. I am not familiar with the growing medium Aunty suggested, but it is likely to be equal parts perlite (or sand) and sphagnum peat, or similar; if you can find that mix, great, or you can replicate it. Ratio Aunty suggested is also fine. The important thing is that the soil should be devoid of nutrients, or close to it. No compost. Fertilizer will kill your flytrap. You can top dress with long-fiber sphagnum if you like. A group of them in a dish garden looks good.
Keep the pot in standing water at all times (a 6-inch plastic pot sitting in a tray 1 inch deep filled with water will do). Never allow the soil to dry out completely. The flytrap requires mineral-free water. So bottled distilled water, or collected rain water are best.
The healthiest flytraps are grown outdoors in full sun. Plants grown indoors may be spindly and lack red coloration. Flytraps need winter dormancy of roughly 3 to 4 months. They will need winter protection if it gets colder than -6°C
An outdoor flytrap will catch it's own insects. No need to feed it, but if you do, use insects (hamburger is sometimes suggested, but will usually kill the leaf). Remember that each trap is only capable of opening and closing about 3 times.
Good luck!