The site for do-it-yourself guitar electronic effects building.  
Visit the archived "schematics" page for effects circuits, check the "beginners" page for instructional information for first-time builders, select the "design" page for learning theory behind some effects circuits, jump to the "parts" page to order some hard-to-find pedal parts, or browse the "sponsors" page to discover books and related products for every guitar/bass effects pedal enthusiast - and to help support Effectronics along the way.  
Beginner project is an Electra Distortion pedal. You can also build the Booster off of Aron's DIY Stompboxes as a good first project. Both would run you under $20.