How much would it cost to ship a few items from cincy, OH to las vegas? What is the most reliable company?

I am moving across country and the items will be things like a bed and tv stuff like that...

You can contact a few moving companies and get quotes. Planes United is one of the largest moving companies in the Cincinnati area with a pretty low claims rate.

UPS...DEPENDING ON WEIGHT

Check out ups....or dhl....or go postal...

https://sss-web.usps.com/cns/landing
The cheapest way to go is with the United States Postal Service....here is the Click n Ship site.....enter the zipcode or destination...then you need to weigh the package....finished. Pay for it online...and print out the label.....slap it on the package and drop it off at the PO...or let them pick it up...or catch your postal carrier and they will take it in for you....all ready to go

The items you are talking about may be costly to ship via ups or dhl. You may look to carriers like roadway express or averitt. They charge by weight and distance but will be cheaper. You can package the items on skids and will be cheaper.

Its going to cost A LOT. Possibly more than the items are worth, depending on how high end your stuff is. Have you thought about driving a small U-Haul yourself? That wont be cheap (something like $25 a day and another 50 cents a mile and the price of gas), but it would likely be your cheapest option.
There are a number of places you can get free comparison quotes. I am posting a link to one such site below. Itshard telling since I dont know exactly how much stuff you are talking about, but I would guess it will likely run you in the neighborhood of $3000-$4000 at least to have movers do it for you.