I've just gone through the wringer buying in Denia.. been here since April, and I've focussed on doing the same as you.. trying to keep costs down.
So do obvious things like cutting down on (expensive) electricity by buying a wood or pellet burner, and install ceiling fans in every room, and never use the aircon.
Also, consider buying a 'casa suelta' ie. not part of an urbanisation with monthly communidad costs. Or buy a townhouse in Denia town centre. Tha's 75-250 EUR a month you don't have to pay out.
In Denia specifically(compared to Javea), generally the plot sizes are smaller, and I have a 340m2 house, and in Las Marinas (Denia+2km), and pay around 400 EUR a year IBI. So buying a decent house on a small plot will obviously keep your annual running costs down.
Watch out as ADSL degrades badly out of Denia town central (+1KM). I am 2KM, and have 1MBs, which is crap, so I paid for a Wimax wifi solution, and pay about 25 EUR pm for 4MBs, but I could pay more and get higher bandwidth, which obviously costs more... so you need to factor that into your bills (on top of your phone line costs) if you want to watch videos online or make sure you buy somewhere very close to the town centre.
Then there's transport costs if you are out of town, with infrequent buses at this time of the year (1 per hour down to las marinas).
So yep, 1K a month is possible, with a carefully chosen small plot and investment in avoiding electricity, and if you are near town / keep the transport costs down.
The biggest problems that I had in Denia (thought it applies to all of spain -;)
1. dodgy property agents, who just plain lie about everything. Never ask them anything verbally, always demand documents, and get them checked if you don't speak fluently, as they lie about the purpose, scope of the documents they send to you. They will lie once, get caught out, and just continue lying.
2. solicitors who are incompetent and untrustworthy.. they just want you to sign the purchase paperwork so they get their fee, and to hell with your best interests. Don't expect any useful information from them.. you have to know the whole process and double check everything they do with a native speaker, especially re: habitation certificates.
3. getting residence if v. difficult.. queing up at Denia foreigners office at 6am on Friday to get an appointment to see someone the next week. You will need to prove you have FULL private medical coverage, including surgery, or your employer is giving you medical coverage. You will also need 7.5K in a spanish bank, and a certificate from the bank to prove that you have the the 7.5 funds(not a bank statement, a specific document you need to ask the bank for).
4. if you are transfering the property purchase costs (deposit and principal) from outside the EU, as I was, you will hit problems - some banks will roast you alive on where the money came from. ie. you will need a 100% watertight audit trail.. original statements, showing how large sums of money have moved between the EU and AUS. And even then, they will probably say 'well, we can see that you have X going into AUS, and you want to take out Y for the purchase', but how can we be sure X and Y are the same money? Then you will have to provide bank statement of all your accounts worldwide going back years. Avoid Banco Sabadell!.. BBVA was a much easier ride. The banks will talk about their 'compliance team' when asking for evidence.. shorthand for the government. And they won't ask for it all at once.. just drip, drip, question after question, week after week, as they build up your financial profile.
Given problems 1..4, living on 1K a month ? I promise you that's the least of your problems.
All that said, I've gone through the wringer over 6 months, have the efficient house, residency and padron, and I love it here. But get your audit trail bulletproof before you begin, or else it will be a nightmare. Start asking your AUS banks for statements going back years right now (before you close any accounts), should they start to shake you down over your financial affairs.
Best of luck!
Jon.