Personal opinion, (others may differ) I wouldn't use the Ready, Fire, Aim method. Pick one or two methods to try for at least six months to test market. Any shorter and you won't know what could have been very successful. Keep in mind that Response Rate is meaningless, close rate is what is important and many people forget that. Minimize the looky loos as much as possible.
Radio ads are expensive and not targeted. Thousands will hear the ad but few will remember the phone number to call. Cost per deal could be high.
Direct mail - Can be very successful but $1K per month is too low. Pick a very specific list. Probate, 50% or more equity, owns private notes, non-owner occupied, etc.. Then by Zip code, age, owns multiple properties, etc. Direct mail works only if done consistently for many months. It is true in real estate that most of your business will come from the 5th - 8th contact (letters, postcards, phone calls.)
Facebook OK if you are marketing to the under 55 crowd which won't be the high equity group, generally.
Bandit signs - can be very successful but almost all communities have laws against them. Plus neighbors delight in ripping them up. Also, must only be put out Friday evening and picked up Sunday evening to avoid the city code people and a fine. You will need to hire someone to do that or it's a big waste of your time.
Door knocking - one of my favorites. But again focus. Are you just wandering house to house and hoping someone wants to sell or knows someone who does. That can be successful but maybe not for the time involved. Pick a niche. I market this way to pre-foreclosure lists. Many of these people have disconnected their phone and few investors call on them. But the presentation is critical. Do not say "You're going to lose your house. Sell it to me." The last thing most people in foreclosure want is to move from their house. Instead, discuss what the options are for someone facing foreclosure to possibly keep their house. There are about eight or nine. (Hint, selling the house is last on the list. I don't mention it on the first visit.) You want to be seen as helpful, not as (in their mind) one of the vulture realtors who just want a listing, a greedy investor who wants to "steal" their house, or the slimy attorney who just wants $5,000 to file bankruptcy, 85 - 90% of which fail.
Bankruptcy - I market to this group, but several things to remember. It's very time consuming, expensive and complicated. You will never get a wholesale deal from someone currently in bankruptcy because the BK Trustee will insist that any sale be at a minimum of 90% of a BPO. The only purpose of the Trustee is to see that as many creditors are paid as possible. They have no interest in you getting a good deal. You will have to learn the federal PACER system www.pacer.gov which charges $0.10 per page to view the file documents. Trust me, this can add up very fast if you don't learn specifically what to look for. My first quarter billing was over $2,000. Now it's about $500. The only way to succeed is to market to people who have either had their BK case dismissed by the court (usually for failure to file documents timely) or if a lender files a Motion For Relief From Stay (because plan payments are not being made) AND the court grants that motion. Just filing the motion doesn't count. If either of these two happen the court is no longer involved, at least with the house.
I know a couple of very successful investors that run an ad in the local penny saver paper. It's not their only marketing, but it does get business. They buy a year's worth of ads at a time and have been running the same ad for many years.
I would ask the obvious question, if you are doing over 100 rehabs in 18 months, what marketing are you using now? That number would be considered a big success by many investors.