With spending for defense, farm price supports, unemployment benefits and Medicare running lower than expected, the federal budget deficit for fiscal 1983 could turn out to be $200 billion or less, some $10 billion below the Reagan administrationÛªs mid-July estimate.</br></br>Officials at the Congressional Budget Office and a number of private forecasters estimating the lower spending figures for the fiscal year ending next week say a variety of factors are responsible, including lower fuel costs at the Department of Defense and the summer-long drought that has induced many farmers to sell grain and pay off outstanding government loans.</br></br>Outlays probably will turn out to be $800 billion, compared with an administration estimate of $809.8 billion, the sources say. The recent sale by the government of Chrysler Corp. stock warrants netted $311 million, while the Export-Import Bank received an unexpected repayment of $400 million from the Iranian government. That $711 million is shown as receipts that lower outlays.</br></br>Meanwhile, the economic recovery has so far produced no surge in revenues, which are still pegged close to $600 billion.</br></br>At the level of $200 billion, the deficit will still be nearly twice the size of the $110.6 billion gap between spending and receipts in 1982. Forecasts for coming years indicate the red ink will remain in the $200 billion range or higher unless Congress and the president take new steps to cut spending or raise taxes.