You don't have to give your cc info, and for $7.80/day + $15/day for mandatory insurance it seems like it's worth investigating.
1- you cant be talking about the 1st 1 of those 2 since even thou it lets U chose which Ins U want to take it clearly says in Red " Please Note! Insurance coverage are Mandatory, will be charged at time of rental". so you will have nothing to Dispute with your CC.
for #2 they dont show everything so be prepared that it will be there somewhere on the contract, the last thing I want to do is spend alot of time reading everything on all sides of those contracts instead of driving away. To each their own.
Now the savings of $7.80/day + $15 for ins is from where?? and what rental company did you get aquote from to compare? Just cause you may not have found the cheapest legit 1 doesnt mean much. My $6 I mentioned above wasnt per day but over 5 days or $1.20 a day