You too can own something from "The Treasure Houses of Britain," still drawing hordes at the National Gallery of Art. From the show, not the houses, that is: In a marketing experiment, the National Trust of England has commissioned expensive replicas of the objects displayed at the exhibition.

The replicas are not your garden-variety souvenirs. There is, for instance, the resin reproduction of a 1st-century basalt bust of Mark Antony from Kingston Lacy House for $1,250. Or the 18th-century sterling silver toilet box for $1,750. This could be quite a moneymaker for the National Trust, whose chairman of the board, Lord Gibson, has expressed interest in improving the quality of museum shop merchandise and curiosity about whether this sort of thing will find American buyers.

Of course, you could just buy one of the pricey items out of sheer sympathy: The artisans who have crafted these replicas are reportedly a dying breed. Buy one and keep them in business, suggests the National Trust's public relations representative in the United States. Items can be purchased at the Smithsonian's Arts and Industries Building, 900 Jefferson Dr. SW. Studio Gallery Show

Studio Gallery, which bills itself as "Washington's oldest cooperative gallery," will be moving out of the Lansburgh building, 420 Seventh St. NW, with the rest of the tenants sometime after Jan. 31. So, appropriately, its last group membership show in that space is called "The Last Picture Show." It runs through Saturday and features the work of new members in a variety of media. Though the Studio Gallery is not exactly sure when it will close its doors, gallery manager Kay Kaiser hopes to have a January show of artists from Alexandria's Torpedo Factory. For more information call 393-6266. NEA Grants

Four Washington-based cultural organizations have been awarded $40,000 in yet another round of grants from the National Endowment for the Arts. The Washington grants are but a small chunk of the $495,120 in arts service project grants that were awarded nationwide in early December. The grants are intended to assist arts groups in hiring professional managers who could improve administrative capabilities.

The National Council on the Aging received $30,000, the Washington Project for the Arts $5,000, the Cultural Alliance of Greater Washington $5,000 and the National Association of Artists' Organizations $10,000 for, among other ventures, updating the National Directory of Artists Organizations. An expanded directory will be published in spring 1986. Artists' Retreats

At various moments in their lives, writers, artists and musicians all yearn for a quiet retreat away from what, at times, can be a tense, distracting urban environment. Artists colonies have provided that solitude for those who need it. Some of them are famous: Yaddo, MacDowell -- "the granddaddy colonies" -- and others have been the scene of intense creativity as well as a respite from that same creative urge. To help those artists who wish to take advantage of such solitude, the NEA recently announced $207,500 in grants to 15 such bases around the country. 'Third World America'

An auction at the Addison Ripley Gallery last week raised close to $6,500 for the purchase of a James Earl Reid kinetic sculpture, "Third World America" -- depicting a homeless family on a heating grate -- which has been commissioned by the Community for Creative Non-Violence . . . George Washington University is offering a free poetry translation workshop through the Jenny McKean Moore Fund for Writers, Jan. 16 to April 17. Jan. 2 is the deadline for applications. For more information, call 676-6180 . . . World Bank and International Monetary Fund employes are sponsoring a performance by "El Tayrona," a Colombian ethnic music and folklore group, at noon Friday to benefit the Colombian Relief Fund. Donations will be taken at the door . . . The James McLaughlin Memorial Staff Show, one of the few public shows of museum staff art in town, and the only museum show where you can buy exhibited works, continues through Jan. 7 at the Phillips Collection (387-2151) . . . Three Henry Moore sculptures from the George and Virginia Ablah Collection have been loaned to the National Gallery of Art; the bronzes have been placed in a landscaped area along the north wall of the Gallery's East Building.