You should be able to DIY a hitch and buy it for $150 usd. I did it on my sedan body car and took about 1hr following a YouTube (you only need utility knife and a basic ratchet set). Thule rear hitch bike rack where the bikes secure to the top tube should cost about $250-300 (I got a discounted model new for $200). So you’ll be in for $400 usd. If you had to pay for hitch installation, prob make that $500-600 usd.
If you can’t do that, sure get a roof before you buy one of those hanging rear. But certainly hitch rear > roof