[renormalised (Carl)]

If you do decide to go for a mirrored scope, a good combo that I would suggest to you is to replace the SWED BD100 I first mentioned with a GSO RC8 ($1199 at Bintel). The FL is not too long (f8...1600mm) that it won't be too difficult to handle with a separate autoguider setup. However, if you have to go the OAG (Off Axis Guider) route, a good one that quite a few use is the Orion Deluxe OAG ($169). But as Greg has said, starting off with a short focus refractor will be easier. More forgiving, especially when it comes to guiding and guiding errors.

If you want a triplet refractor that will help come in under your $4000 budget, you may have to compromise on the aperture as a good 4" triplet will set you back at least $2500. So, you may have to go with a 80-90mm refractor. Even these can be pricey...(a WO FLT98CF will set you back $2999...the AL tube version is $2499), but you can get a Meade Series 5000 80mm apo for $950. The only apo of 4" I've seen at a "bargain basement" price is the Meade Series 5000, which is $1800. Most will be considerably dearer. But if you stretch your budget for a good 4" apo triplet, there are some really nice scopes on the market.