The development cost of creating a token will probably be the same based on the network you are using, ethereum is usually more expensive but others are cheaper. But the difficult thing about being stable a coin is that there has to be a guarantee for the coin to be stable in order to keep its price constant. Examples like USDT which is said to be backed up by fiat USD, terra UST which is backed up by bitcoin. but my advice to build a stable coin must be with a real asset collateral, such as a company, land, gold, silver, or anything that can generate real and sustainable.