Get 2 Coleman Sundome 4 person tents ($42 on Amazon), or one Coleman Sundome 6 person tent ($90). You should also invest in an EZ up (AKA pop up) canopy. Slant leg 10x10 ozark trail canopy is like $45 at walmart.com right now.

For beds, unless you;re trying to invest in something that you'll use over and over again after Firefly, just get some air mattresses. You're going to be on grass so an air mattress should last you through the weekend fine and be comfortable enough.

Coleman queen size air mattress ($23 on amazon) https://www.amazon.com/dp/B01M0BPG26/ref=sspa_dk_hqp_detail_aax_0?th=1&psc=1

Etekcity rechargeable air pump ($26 on amazon) https://www.amazon.com/Etekcity-Electric-Rechargeable-Quick-Fill-Inflatables/dp/B07CTF8TS8/ref=sr_1_3?keywords=air+mattress+rechargable&qid=1556044876&s=gateway&sr=8-3

If you really want cots, I suggest these as they're light but comfortable - Byer Allagash cot (2 for $111 on Amazon) https://www.amazon.com/BYER-MAINE-Allagash-Lightweight-250lbs/dp/B07KJKDB5N/ref=sr_1_fkmrnull_1?keywords=byer+allagash&qid=1556045223&s=gateway&sr=8-1-fkmrnull

Otherwise the cheapest cot you'll find will probably be the Coleman ones which are about $35 each on Amazon. But they're bulky and heavy.