You have 2 great comments… Schwim regarding what to look for in a frame and Plusbike Nerd about the costs…
My recommendation (cost wise and bike wise) is to buy a new or used bike with the help of financing if possible. There are more and more brands accepting PayPal or Affirm… That way, you can get an updated bike and pay small monthly fees (sometimes without interests)… If you don’t have good credit or credit options, a friend or relative might.
I did build up my “entry level” bike and now it must be the most expensive bike in the world without being the best bike. Don’t make the same mistake I did. So, try to get financing or save money and use it when the time is right. Look for offers, promotions in outgoing models. Look for Direct to Consumer brands instead of trendy brands with distributors. Direct to consumer brands have better components for the same price. There are also some Direct to Consumer brands that also sell frames only in case you want to follow that route. Hope my experience might help you with your decision.