MOH issues

My MOH is older than the rest of the BM's, she is in her 50's. She is like a second mom to me, I have known her my whole life, our families are extremely close, and I wanted her to be in the wedding, so I asked her to be matron of honor.
Now here's the problem- she wants to go and buy whatever she wants for the wedding. I don't like this because, first of all she is very extravagant and she would buy something very expensive and show up my BM's.
Second, I want the color she wears to match the color the BM's are wearing. The colors we are doing are light pink and green, and there are so many shades of those colors that there is a good chance a color by a different designer would be off.
Third, I don't want her to look like she's my mom, because she would wind up getting a dress similar to one my mom would get. A lot of our guests don't know her or my mom, and they would think she is my mom. I also don't want her to show up my mom by getting a much more expensive dress.
So the solution I came up with is that when we picked out the designer for the BM dress (who is Bari Jay) she could pick any dress by that designer and that way it would be in the same dye lot as the rest of the girls.
She doesn't want to do that. She wants to do her own thing.
FH suggested I tell her to buy two dresses, one to match the girls for pics and the ceremony and then whatever she wants for the reception. I haven't told her this suggestion.
I don't want to sound like a Bridezilla, but its important to me that she matches the other BM's in color. Am I being unreasonable?
What should I do?

This is the BM dress:

if shes the moh, she needs to follow the rules that the other bm's are adhereing to.....you get to tell her what to wear.

age doesnt factor in- she's there for you, not to look fabulously gauche by wearing whatever she wants.

I say, tell her youre picking the gown...she can totally pull off whatever the other girls are wearing or even just a diff dress from the same line ....Jordan has a few that look more demure for older women

I don't think you are being unreasonable at all...You asked her to be a part of YOUR wedding, and she obviously said yes. So along with accepting your generous offer comes some rules (lack of a better word, but I'm sure you get my drift).. Everyone who is in a bridal party knows this.

I think you are being more than fair with allowing her to choose a dress that she likes within the Bari Jay line so that the color matches. It would be inappropriate for her to wear anything that would upstage your other BM's or most of all, your mom.

I have a similar situation as yours. I have 3 girls in my BP and told them that they can get whatever style dress they want just as long as they’re all the same dye lot so that they match. Since 1 of my sisters lives in CA, they’re all getting dresses from David’s (which is a nationwide chain).

I was a MOH at a friends wedding and her aunt was the matron of honor. Her aunt was a lot older than us and did buy her own dress, same color as ours. It didn’t match exactly, and her dress was not a gown like ours was, but it didn’t look bad in the pictures at all. Personally, I would want them all to match, like you do. So if you feel strongly about it, you should put your foot down with your aunt.