Ibutamoren is better known around here as MK-677, which is a growth hormone secretagogue. It is a ghrelin mimetic, so it makes you really hungry FYI. It works extremely well when used for short lengths of time to increase the release of natural GH, but results fade quickly after a couple weeks due most likely to pituitary fatigue (production cannot keep up with release). You can find MK MUCH cheaper from a couple reputable suppliers on here. DQ being one of them.
Sermorelin, aka Mod-GRF 1-29, is a GH releasing hormone that also stimulates the pituitary to release a small but steady leak of GH as opposed to a large pulse. You can find it substantially less expensive from even the best of sources here, like PSL.
I've only used Mod-GRF in conjunction with GHRPs (kinda similar to MK) and had great results over time in regards to fat loss and staying lean while eating large amounts of food. You could also go the exogenous GH route, which is more expensive but can be run much longer without a drop, and can also be used in conjunction with these options me
You can definitely get them much cheaper though. By a lot