I have not dealt with Christies for quite awhile (for selling) , but they used to refuse items with a value of $1k ; later on it went up to $2k .
I'm not sure what $ level it's at today/these days .
Large auction houses used to 'consign' artworks & often in their agreements they'd have the option of doing conservation/restoration/reframing to the item , in order to make it more presentable for their sales .
Options for the sellers ( & the auction houses ) used to include such services as a variety of sizes (& prices) of photos included in their auction brochures/catalogs .
In consideration of the costs incurred , especially for items that do not get sold & are sometimes abandoned by the owners , higher limits needed to be in place IMO .
If the potential for profit margins is low , most large auction houses just 'pass' on so-called 'low value' items .
I still say that you've got a cool little painting , mariok54 !