The days of the $500,000 average paycheck are long gone, even at Wall Street’s most gilded firm.

So predicts a report issued Thursday by Credit Suisse analyst Howard Chen. He slashed his fourth-quarter earnings estimate on Goldman Sachs (GS) to $3.70 a share from $5.08, citing its latest soft trading quarter and higher non-compensation expenses.

“Due to persisting choppy market conditions and our expectations for a weaker finish to 2010 for fixed income sales & trading, we reduce our forward estimates,” he wrote in a note to clients.

Chen continues to rate the stock buy, thanks in part to what he calls “continued expense discipline” at the firm. He expects Goldman to set aside a little more for pay and perks this year than last, but to be far thriftier on that front than it has for most of its public history.

He estimates the firm will devote 40% of 2010  revenue to cover employee-related costs. That would bring the firm’s compensation expense for the year to $15.8 billion, or around $446,327 for each of the firm’s 35,000 or so employees as of September.

That compares with the $498,000 average the firm arrived at last year, after an unusual year-end bonus pool reduction, and the $662,000 peak the Goldman payout reached in the bubble year of 2007.

Strong results in the first half of 2010 helped launch Goldman on what looked like a track for a return to a $500,000-plus average payout. But the firm suffered along with Morgan Stanley (MS) and the rest of Wall Street in a summer trading slowdown, and execs presumably remain loath to bring on any more bonus rage than is necessary.

Chen isn’t the only one who sees Goldman paying less. David Hilder, an analyst at Susquehanna who also rates Goldman stock buy, predicted last week that Goldman would set aside 39.5% of 2010 revenue aside for employee pay. That’s up from last year’s 36% but remains the second-lowest figure in the decade or so since the firm went public.

Goldman shares were flat Thursday and are down less than 1% for the year.