(edited by Tou.3078)
Bifrost
Neither is cheap. If you have that much gold, just buy it, and use every you have accumulated to chase another.
Angelina is free game again.
Crystal Desert
Crystal Desert
Making the legendary is mostly (always) cheaper than buying it, that’s how people make money building legendarys.
If in doubt, check http://gw2legends.net/
You just need to decide if the not directly priced materials (karma, skill points) are worth the gold gain you get.