Hi I've been wanting a custom version of a trick called "simplex monte" by alakazam magic where the gimmick is made with different backed cards of my choice, and I was wondering does anyone know if they make custom gimmicks on request? Thanks

I doubt Alakazam would do it, but there are custom gaff builders on the Café that may be able to help you out.

http://www.cardgaffs.com/
https://www.facebook.com/CardMakerBerndMaucksch
http://www.martinismagic.com/Products.html
https://www.facebook.com/Gaffing101/

Some others I have come across, but not used, so caveat emptor:

Print By Magic - Custom card printing on Bicycle stock: http://printbymagic.com

Adams Gaff Co - Custom Gaff Cards: https://www.etsy.com/shop/kennyadamsgaffs

The Card Plant: http://www.thecardplant.com/category/gaffed-cards

Mimesis Magic: Hand produced gaffs and gaff decks: http://www.mimesis-magic.com/index.html