Hey there, Peggy!
You should get estimates upon which you can rely to make a decision. The rule of thumb is to get at least three–get them free, too.
Incidentally, here’s a great handyman site that has a section devoted to gutters and roofing. There, scroll down a bit and you’ll find a text-link kind of in the middle of the page that offers up to four (4) free estimates from gutter contractors in your area who would be in the position to provide you a free estimate of the cost of installing the 70 feet of gutters and gutter guards, all without obligation to you (the text-link says, "Find Roofing…Gutter Service Contractors. Get Up to 4 Quotes Now…Free"):
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Home_Improvement_Zone_Roofs_Components_Gutters.htm
Getting many estimates is key to becoming an informed consumer seeking to avoid the wrath of roof/gutter contractors who choose to prey on the ill-informed consumer. Good luck!