Another consideration, if you have a subpanel in the shop and you are just tight for circuit spaces to use quaduplex breaker (dual tandem with interposer) like: Eaton BQ230230 Type BQ Quadplex Circuit Breaker, 120/240 VAC, 30/30A, they come in different current ratings.
If you don't have a subpanel in the shop (e.g. running dedicated 240V/30A feed from main house), you can add a tiny subpanel just for the two 240V outlets like this: 2-Space 4-Circuit Indoor Single-Phase Main Lug Circuit Breaker Panel ($19.45 at HD) and use a quadplex breaker (of course, you may also use a larger 4-space subpanel if you prefer the regular breakers).
Edit: do not bond/connect the grounds and neutrals in a subpanel, that is only done in the main panel. If your wiring requires 4-wire outlets (2xHot, Neutral & Gnd), you will need to install an additional ground bar/strip inside the metal subpanel box that is not bonded to the neutrals of the subpanel.