Saltwater isn't really that difficult. For an anemone, you need to keep your water pristine and they require intense lighting to survive. Your largest expense will be lighting. I'd suggest looking into the taotronics LEDs, as they are intense lights that won't need any bulbs replaced every 6 months to a year like bulbed units require.
To keep water pristine, you will want to use ro
water OR distilled water at best. A ro
machine is a great addition...but you can put it off if budget doesn't allow. My ro
is down currently, and have been using distilled water from Walmart for almost 2 years because of it.