Originally Posted by
Coh3n
I can tell you what I did. It's not exactly fast, but it will make it cheaper for you. If Summoning happens to be your lowest skill then you can use Tears of Guthix once a week. I would also suggest doing the Penguin Hide and Seek once a week as you can get over 20k experience in a skill of your choice. Since you summoning is that low you'll gain levels pretty fast.
If you're going to do this you need to do Cold Storage quest so you get extra experience when you do the Penguin Hide and Seek. In between doing the Hide and Seek and Guthix Tears, you can fight whatever monster drops a lot of charms. (I don't do combat that often, so I'm not exactly sure which monster would be best for dropping charms, sorry).
I hope I helped. :)