I have some templates on my home computer. I can send you them later. A couple asthetic notes: the card name and type text is better simulated by the free font Optimus Princeps, which you can easily find and download. The card text is Times New Roman. Using these will make the card look a bit more like a real Dominion card.
Houdini--I like the general idea for the overpay. As for the main part of the card, I wonder if it might be better to have the card trashed rather than returned to the supply.
Biking: you have the discard effect twice on there. I think I see you trying to make a differentiation, but it runs into some confusion. If I might suggest a more "official" wording: "When another player plays an Attack card, you may discard this. If you do, gain a Silver. The top half seems a bit weak, or maybe just a bit more niche. But it also seems like it anti-synergizes with the reaction effect of gaining more silvers. The card's action seems like it favors a deck with few treasures, and coppers at that. It also does not stack very well, despite its +Action. I would suggest reworking the top half to be more useful, or strengthen the bottom significantly. (Maybe: When you discard this other than during clean-up, you may gain a Silver, putting it on top of your deck.)