Depending upon the size of your yard and the amount of weed eating and edging you need to do, the rechargeables are getting very competitive. Most have a swivel head so they can be used as a weed eater, or can run vertically as an edger. They are light weight, do not require mixing fuel, or power cords....and if you have a large yard, get a spare battery you can probably do everything without having to wait to recharge a battery to finish.
The best rechargeables run about $130-$160.
...Rich