I have a similar unit to the Instant Pot, the Breville Fast Slow Pro [BPR700]. A great, versatile unit.
I DIY'ed a Souse Vide cooker with a Chinese eBay controller and a 6-quart Crock Pot oval Slow Cooker, along with a Vacuum Bagger would be under $200.00.
Another great combo is an Iwatani [Japan] Butane Cooker, your wok or a cast iron grill. Steaks to Stir-Fries and Butane doesn't leave a taste and is OK for indoor use (unlike Propane). Under $100 for the three combined, easy.