I rather you save up your money and teach yourself how to build one yourself so you can build your own desktop yourself (God, that is confusing).
You can try searching 'LinusTechTips' on how to build your own computer or even search it up on Google, it is really simple and I myself built my own computer because I took the initiative to teach myself how to.
Really, a pre-built computer that cost $600 vs a hand-built computer that cost $700 is more worthwhile and lasts longer. (I owned an Acer Aspire for 2 years, it was labelled as a 'gaming' computer with a GT530, can you fucking believe it?)
P.S If you are actually comtemplating on building your own desktop, don't buy low-profile cards, they are a waste of money.