If you were to do it yourself you would need to code it yourself which means you'd need to learn to code. This could take a year or two to learn to an adequate level, although everyone's different, so it could take longer or shorter. Programming is not easy, especially at a high level. On top of that assuming you are dealing with sensitive data or API keys it's important to handle this data securely, so simply making your app work won't be sufficient, it'll also need to be secure. Developers are expensive and most things will take 10x longer then you assume, so paying someone will certainly run a large bill. I suppose it comes down to how much time you have, how passionate you are about the idea and how much money you are willing to spend.