Studios like to have time booked in advance and offer discounts for pre-purchasing blocks. Some even offer discounts for cash. Some studios will charge more for an engineer and even offer a producer for an hourly rate. There will be extra charges for media too. One will usually do the job.
Some studios offer in house mastering, artwork, and even bulk CD orders for a price.
Take all this into consideration before making your choice. Remember that your CD will be a representation of your band and will be around forever. You will want to be proud of it when you force your friends and family listen to it over and over again. If you have a keyboard player ask if you need an amp, or if they will sequence it with a computer. If you do your own MIDI programming you may want to bring that along with your sound modules.