I have a nice regular tripod (503HDV,351MVB2K), but would love to have one for filming low to the ground as well.

Any suggestions?

You mean a hi hat?
http://search.store.yahoo.com/cgi-bin/nsearch

Try this: http://www.bhphotovideo.com/c/product/366660-REG/Bogen_Manfrotto_529B_529_Hi_Hat.html

Today I purchased a Miller Safari tripod. I hadn't heard of it before, but was looking for something cheap(er) with a fluid head. Came across this badboy for 400, and got the price down to 350 for buying it on the spot. It's got a 55mm bowl head, and is incredibly smooth. The greatest part, it has angle locking legs so you can literally lay the tripod to the ground and get the low shots you need. Payload is 11 lbs, weighs about 8 lbs itself. Have a look...

http://safaritripod.com/

Very pleased with it, I recommend.

If you want to go on the cheap then use your 503 head with the 3221 legs.
http://www.bhphotovideo.com/bnh/controller/home?ci=0&sb=ps&pn=1&sq=desc&InitialSearch=yes&O=jsp%2Fproduct.jsp&A=search&Q=*&bhs=t&shs=3221+legs&sb=ps&pn=1&sq=desc&InitialSearch=yes&O=jsp%2Fproduct.jsp&A=search&Q=*&bhs=t
I also use the half/ball leveler #3502 between the legs and head. I know it shows a center column but you can remove that and it includes a short plug adapter for the head. Goes down to 3.5 inches plus the height of the head.

Andrew,
I'm curious what makes you think this tripod is from Miller? I don't see anything about Miller on the Safari website, or in the instruction manual. The head greatly resembles the 717A fluid Head from Weifeng, which is available on eBay. Who makes it isn't as important as whether it works well; I'm glad to hear it operates smoothly.
Best,
Peter
www.parkfilms.com

Good call,

I realized that after I posted. The vendor I bought it from (Washington Professional Systems [www.wpsworld.com] ) mentioned to me that Safari is a sub-section of Miller. I spoke out of context, apologies.

The Gitzo GT3540XLS tripod can do ground level work and works great with the manfrotto 3502 leveler and Gitzo G2180 Head makes a great lightweight
tripod at about 7.5 lbs.

The Gitzo GT3540XLS tripod can do ground level work and works great with the manfrotto 3502 leveler and Gitzo G2180 Head makes a great lightweight
tripod at about 7.5 lbs.

My pet peeve with the G2180 is its lack of a bubble level. I find it awkward to level a tripod without one. Otherwise its a really nice mini fluid head.

Best,
Peter

Here is 503 with the Manfrotto 3221, with post pulled for lowest level capability.

weifeng has a lot of tripods from ultracheap to mid-expensive. (in the e-image serie)
take a look on their website, you will probably find the safari twin brother
http://www.weifengchina.com/pro/index.asp?page=1&id=135

I read in one of the trade magazines a while back that the Chinese knockoffs really do a good job cosmetically cloning other makers tripods, but it said that's about where it ends. Functional-wise you might be disappointed.

I'm not saying this particular company... just in general. Just a heads up :)

got a EI717 for $140, looks like a $600+ tripod, put my FX1 on it... and it doesn't fall (yet).
admittedly, yes it is just a bunch of tubes painted in black. but at that price , i am happy.